PHILADELPHIA -- Injuries can leave mental scars along with the physical. Trainer Steven Whitehead knows this from experience, and immediately recognized the signs in Philadelphia Eagles cornerback Sidney Jones.

When Whitehead first encountered Jones this spring while interning with the Eagles, he was alone in the team weight room, wearing a lifting belt to do 135-pound back squats.

"The problem wasn't that he was doing 135 pounds," Whitehead said. "The problem was that he was doing it with a belt on. A belt is used once you get to heavier weights. He was so scared of hurting himself that he was using it with just a plate on the bar.

"I had to get him to take it off and educate him through the process of building his body back up. Sidney just needed confidence and someone to believe in him and show him the right direction."

Jones' young NFL career has been overwhelmed by injury. Projected by some to be a top-15 pick in the 2017 NFL draft, the University of Washington standout tore his Achilles at his pro day. He dropped to the second round as a result and appeared in just one game as a rookie. Last season, he began dealing with hamstring issues in early October and never got right, missing seven games in all. Trust in his body began to wane, as did his confidence.

This summer, though, has delivered a different Jones. The swagger levels are up and so is the production. He has intercepted Carson Wentz multiple times during training camp while running with the first team, working both at outside cornerback and from the slot. It's the best he has looked since coming into the league, and he hasn't missed a practice.

"I feel better mentally, spiritually and healthwise," Jones said. "I feel really good about everything.”

A key part of the turnaround was his work with Whitehead, who has served as Alshon Jeffery's trainer for several years and, along with his partner Deon Hodges, boasts an Eagles client list that now includes Fletcher Cox, JJ Arcega-Whiteside, Josh Perkins, Greg Ward and Bruce Ellington.

Jones trained with Whitehead in Dallas for a month following organized team activities, during which they attacked the injury issues both physiologically and psychologically. First, Whitehead took the dramatic step of changing how Jones runs. Jones had a tendency to over-stride, so Whitehead got him to shorten his stride and correct his posture to take pressure off his hamstrings and allow him to run with more power.

"When I tell a guy to run the way I want him to run, you should see the look on their face," Whitehead said with a laugh.

"It is kind of weird knowing you haven't been running right your whole life and you start to run with form," Jones added. "And then you get in this weird place where you know what it feels like, you know the difference between your old self and what it's supposed to feel like. The challenge is trying to find that consistency of the new because you could easily fall back into the old."

To get past the mental blocks, Jones had to develop a better understanding of which types of pain and soreness you can push through, and which types you can't. Jones explained that following significant injury, "anything else in your body hurting might trigger that same type of mental confusion," making it essential that you're well-educated on what the real warning signs are.

Whitehead became very knowledgeable in this realm through experience. A former football player himself, he had several surgeries over his career: a knee surgery in high school; two more knee surgeries in college to go with hip labrum repair; and a torn shoulder labrum, broken back and two more knee surgeries in the Arena League. Once Jones heard that, he knew Whitehead had an understanding of where he was coming from.

"Knowing when to shut it down and when to push through," Jones said. "I've made that mistake even with my Achilles. It was hurting before that [pro day when it ruptured] but it was the football mentality of pushing through and that's what got me. If I would have sat out and gave it time to rest, who knows? Hamstring, same thing, I probably wasn't ready but the football mentality kicked in."

New Orleans Saints coach Sean Payton seemed to know Jones was not ready for game action when he constructed his game plan for the Eagles in mid-November.

"We gotta run right at 22 and we gotta throw at 22," he told his coaching staff the night before the game, according to NBC Sports. "We're gonna make him defend the run on the first play. We're going after him on three of the first eight plays."

Sure enough, Payton dialed up a Mark Ingram run right at Jones on the Saints' first offensive play. Ingram barreled through an attempted tackle by Jones and broke off a 38-yard run. Jones was playing in his first game following an extended absence because of the hamstring injury. Payton predicted Jones wouldn't hold up, and he was right. Jones aggravated the injury and was knocked out of the game. Its secondary decimated, Philly was crushed 48-7 -- the worst defeat of a defending Super Bowl champion in NFL history.

"I didn't use that as my motivation, but I'm glad you brought that up. That's another thing [I can use]," Jones said after a training camp practice this summer. "For me, it's all about personal growth right now. That's the time of year I'm in right now. So I appreciate you bringing that up for me. But I mean, good game plan for them. They were smart about it."

It was a low point: the highly touted corner openly targeted by the opposition. Since then, it's been a steady climb back up, with Jones showing encouraging signs that he is starting to see some payoff in Year 3 after what defensive coordinator Jim Schwartz called some "expensive start-up costs."

"The main thing is just getting him to be comfortable with his body. Going through those injuries, you start to forget how your body actually felt prior to it," Whitehead said. "That was the main thing was getting him back to understanding who he was, and I think he actually did that."