Editor's note: Philadelphia Eagles running back Darren Sproles announced he would retire at the end of the season. Here is the story of his journey into the NFL.

PHILADELPHIA -- Safety Malcolm Jenkins was asked for a favorite memory of running back Darren Sproles, and instead offered a striking thought.

"Every time I think about Darren, it's really one thing that constantly pops into my head," Jenkins said of his Philadelphia Eagles teammate. "He makes you reconsider if you want to be great."

He makes you reconsider if you want to be great.

Jenkins has seen Sproles' meticulous approach up close for nine years now -- first as his teammate with the New Orleans Saints and now in Philadelphia. He knows how hard Sproles trains. How he takes care of his body. How he always goes full speed at practice, even at age 36. That he habitually finishes every rep, not stopping until he's in the end zone. That he has done this day after day, year after year, without complaint. Jenkins, like most who have come into contact with Sproles, marvels.

"Not many people can emulate that, which is why he is where he is," Jenkins said.

Sproles moved into fifth place all-time in NFL all-purpose yards, jumping over Tim Brown (19,682) and into the company of Jerry Rice (23,546), Brian Mitchell (23,330), Walter Payton (21,803) and Emmitt Smith (21,564).

Not bad for the 5-foot-6 Kansas State product, whose only goal was to prove his critics wrong by lasting more than one year in the NFL. And there have been many critics along the way, dismissing Sproles primarily because of his height.

"It was mainly my parents. They always told me, 'Don't ever let somebody tell you that you can't do anything,'" Sproles said. "And if they do tell you that, you work hard to prove them wrong."

From fighting through preconceptions to overcoming a speech disorder to carrying on after his mother Annette's passing, here is Sproles' story, as told by some of those who helped shape him:

Former Olathe (Kansas) North High School coach Gene Wier: "My daughter and he were in the same grade. She talked about him all the time, and she came home one day in the second or third grade and said, 'Daddy, Tank is moving.' [Sproles' father gave him the nickname Tank because he weighed 10 pounds at birth, and it stuck.] She said, 'He is going to Rolling Ridge,' and I said, 'Well that's good honey, some day he'll go to Olathe North.' And she said, ‘That's what he said he was going to do: He was going to be the next great running back at Olathe North.' That was like second grade.

"If you've ever seen the photos [from Pee Wee football], it's hilarious because he was a little bitty guy. He was just like a little bug scooting through there."

Happy birthday to RB @DarrenSproles, who's been making them miss since his Pop Warner days.#FlyEaglesFly pic.twitter.com/u1mzvan472

— Philadelphia Eagles (@Eagles) June 20, 2017

Olathe North principal and former running backs coach Jason Herman: "Darren was so fast that they said, 'You have to run between the tackles.' If he ran a sweep, he was gone. There was nothing anyone could do about it so they said he had to stay between the tackles to make the game more fair. Well, that didn't work."

Wier: "The infamous one was his daddy, the first time he ever scored a touchdown, his daddy just reamed him because he spiked the ball. He was in like second or third grade and his dad got after him, and he never did that again.

"The talk, of course, was that when he gets to junior high the kids will catch up to him because they'll get bigger and he's little."

Sproles rushed for more than 5,000 yards, averaged more than eight yards per carry and scored 79 touchdowns at Olathe North, and led the team to three state titles.

Herman: "He was a tiny dude, he was a little guy out there among men, but once he hit the edge, he was gone. The greatest memory has to be against Shawnee Mission West. He's going down the right side, they over-pursue, and he makes a cut and you literally see six guys go to the ground, he cuts up the other side of the field and then untouched, gone."

Wier: "He had a severe stammering problem. He stuttered really bad. ... And he had to give a speech in front of the whole school for winning an award as the outstanding player in Kansas City. So we had to practice that."

Herman: "It's a live television broadcast and the winner has to speak in front of the entire student body. Coach Wier called my wife, who is an English teacher, 'Hey, will you help Darren with his speech?' Because he never spoke in front of people. Darren hopped up in front of our community, in front of our kids, in front of the TV camera and did his speech. He worked really hard at it. And he did a great job."

Wier: "It was brief. Very brief. I know it doesn't sound like much, but it took a lot of courage."

Herman: "I remember telling my buddies who weren't at Olathe North, 'Wait [til] you see this kid at Kansas State. And they're like, 'Yeah, he's too small, he's not going to do anything.'"

Wier: "What they got confused with him was his height is what makes him small but there's nothing small about him. His nickname's Tank and that's for a reason: That guy is strong. He was one of the strongest guys in high school, college, and everywhere else. He's a bodybuilder kind of guy and he runs people over. He's not little, he's just short. I just got tired of it. It was the same question every time. And nobody ever considered him to be a running back in college. Never a thought.

"I would get these calls and they would say, 'What's he going to be? A third-down guy? Punt returner? And I would say, 'One, he was our third-string punt returner.' He tried. And he would go out every day. We would set up a jugs machine for him to practice returning punts because that's all we kept hearing, that he was going to have to be a punt returner in college. So we did that. He couldn't catch them. But he kept going."

Of note, Sproles' nine career return touchdowns (seven punt returns, two kick returns) are tied for sixth most in NFL history.

Sproles was lightly recruited coming out of high school. It came down to Kansas and Kansas State.

Wier: "His mom was sick with cancer. And so he really wanted to go to KU at the beginning. He wanted to be close to her so he could go home when he needed to. That's who he was. He knew the best place for him was K-State, but he wanted to be close to his mom because she was not good."

Former Kansas State running backs coach Michael Smith: "His mom really wanted him to make a decision where he was going to be happy, and I think she gave him her blessing as far as, 'Darren, I'm going to be all right. You need to do you.'

"For a kid -- at the time I think he was 19 years old -- to have to go through that and see his mom suffer and just be gone so fast, I couldn't imagine that. He was crushed. He lost his matriarch. His mom was everything to him. And what we did was Coach [Bill] Snyder, being the coach he was, we packed up a bunch of buses and we drove to Kansas City and went to the funeral. We were there for Darren not only as coaches and teammates but as brothers. I think that meant a lot to Darren. And s---, I think two, three days later he was back in Manhattan going about business as usual."

Sproles racked up more than 5,600 yards from scrimmage and 47 touchdowns at Kansas State, and served as a punt and kick returner. He finished fifth in the Heisman Trophy voting as a junior, and graduated in 2004 with a degree in speech pathology.

Smith: "His senior year, we begged him to come back and he did. We're playing Louisiana early in the season, and Darren runs for like 250 in the game, has some unbelievable numbers, but he fumbled twice. We go in Sunday morning to grade the film -- our staff room overlooked the stadium -- and we just see this guy out there running. Running plays by himself with a ball in his hand. It was Darren. Here's our best player, our All-American, our guy. He knows he's going pro, but just to see him take that part of his game so serious. And what he did is he took the game script out there and ran every play over, and just was carrying the ball, making moves on air. I don't want to make it sound like a movie but it's true, man. The dude was unbelievable. I tell people I've been fortunate to coach a lot of unbelievable players, but by far the best player I've ever coached was Darren."

Sproles was drafted by the San Diego Chargers in the fourth round, 130th overall, in the 2005 NFL draft. He was the 15th running back selected.

Smith: "He was mad. Darren was pissed off and happy at the same time. He was mad because here was a guy that had done so well in college and you'd think after everything he'd proven at the level he had proven it, at some point somebody would say, 'You know what, this guy is the real deal.' To see guys go in front of him that he knew [he was better than was hard]. Even during his rookie year, he was like, 'Coach, they're not playing me. They're not playing me.' I'm like, 'Look, son, learn from one of the best in the business [in LaDainian Tomlinson], and your time is going to come."

Longtime trainer Todd Durkin: "When I think of Darren, I think way back to the days of LaDainian Tomlinson, when LT took Darren under his wing, brought him into the gym. Those two training together was like watching Ali and Frazier train together, man. My first impression is, 'Does this guy really play in the NFL?' He looks like a high school kid. And then when I saw him start to move, I'm like, 'My goodness. I thought LT had fast feet.' This guy had the quickest feet I've ever seen in my life."

Sproles' training partner and quarterback Drew Brees: "He's a stud. One of the greatest teammates I've ever had the chance to play with. I've said it before: I think he's a once-in-a-lifetime player. I love working with him in the offseason. He makes me better. A great friend. So I always root for him."

Durkin: "I remember Darren specifically in a workout with LT, a future Hall of Famer, a guy like Drew, who had won a Super Bowl, and guys like Peanut Tillman, and Sprolsey just setting the tone in that workout. It got raised to an epic, iconic level on all aspects. Work, sweat, intensity, energy. I remember the music pumping. I didn't want that session to end because I knew someday the magic in that room was going to end. And it was Darren that set the tone.

"No one else sees, day in and day out, every single day of the week from February through July, the sacrifice that guy makes to be one of the best all-time. I've been able to see that for 10 years, and it's not a surprise to me that when he gets this mark ... it's not a mistake. It's not something that a 5-6, 190-pound guy just stumbled across success on this. It's truly a testament to his character, his work ethic, his determination, his sacrifice, his everything. It's who Darren Sproles is."

Sproles spent his first six seasons with the Chargers before signing with the Saints as a free agent. After three seasons in New Orleans, he was dealt to Philadelphia in 2014 for a fifth-round pick. Sproles said he found out about the trade on social media, and felt "disrespected" by the way things were handled.

Brees [in 2014]: "It's the same thing that happened with the San Diego Chargers. How could they have let him walk out of that building, you know?"

Both of his old teams were interested in him this past offseason, but Sproles decided to finish his career in Philadelphia. Contemplating retirement for a second straight offseason, his daughter made a deal with him: If she qualified for the Junior Olympics, he had to return for a 15th NFL season. She did, so he did.

Durkin: "Darren, in his deepest of hearts, has always appreciated teams that believed in him. And like I told him before he decided to come back, all you need is one team to want you, to believe in you, to come back. He had other opportunities, but the Eagles I believe put out their best hand to make Darren feel like he was wanted in Philadelphia. And what human being doesn't want to feel wanted?"

Rookie running back Miles Sanders: "That's my dog, man. That's the OG. I told him the first day I met him, I told him, 'For real, you've got all the respect out of me. Being your size, the position that we play in this league, and for you to be here for 15 years, I told him you've got all the respect out of me. I'm in his ear every day, asking him questions, how he thinks on certain runs and certain looks, basically just picking his brain."

Jenkins: "I feel like the last few years, especially with some of the injuries, he's contemplated whether he wants to hang up the cleats or not, I think it's kind of been a year-to-year thing, but I feel like I know him enough to know he can still do it, and he's got something about him that wants to go out with a bang. So it's not surprising for me to see how he's performing this season for us, and I have a feeling this is going to be a special year."

Only 15 players in NFL history standing 5-foot-6 or smaller have reached 1,000 all-purpose yards. No. 2 in that category, Buddy Young (1947-55), finished with 9,593 yards – more than 10,000 less than Sproles. History will judge him not on size but production, and will find in that respect, he stood shoulder to shoulder with Hall of Famers.