Matt Hasselbeck couldn't figure out the answer to his daughter’s math homework. It had been decades since he had taken algebra, and knowledge of quadratic equations can fade with time, replaced with formations and coverages and remembering to pick up the dry cleaning on the way home.

So Hasselbeck turned to the logical place to help: Snapchat. More specifically, a Snapchat group filled with his Indianapolis Colts teammates, friends and guys who were much closer in age to middle school algebra than they were to the guy with teenagers of his own. Andrew Luck, quarterback and Stanford grad, responded and helped answer the question.

Problem solved, until a few days later in school.

"My daughter's seventh-grade teacher was like, 'OK, we've got math homework tonight, and Miss Hasselbeck, please make sure Andrew Luck doesn't do your homework for you tonight,'" Hasselbeck said. "I think that's funny. My kids think that's super embarrassing. I don't know. I thought it was funny."

This was life at 40, which is not a common age for an NFL quarterback. It's usually an age with faux old-man parties and cracks about being over the hill. Most athletes are settling into their second -- or third -- career, with pro sports long concluded due to declining talent, injury or a decision to walk away from the consistent mental and physical grind.

That doesn't seem to bother Tom Brady, who turns 40 on Thursday. He'll be the 20th quarterback to play after his 40th birthday. He'll likely be joined by Drew Brees, who turns 40 in January 2019, and perhaps by 33-year-old Aaron Rodgers someday.

While younger quarterbacks might be more concerned with dating, diaper changing or playing FIFA, quarterbacking at 40 is different. For some, when the 40-year-old comes home from his NFL office, "Dad Mode" begins, including counseling kids and, yes, helping with homework just like any other middle-aged father balancing a demanding job with a growing family.

"I remember sitting there saying, 'There's no way Blake Bortles is doing this this week. He doesn't have this problem. He’s chilling,'" Hasselbeck said. "He's like, 'Am I going to play Halo tonight or not?' That's where he was at."

Brady has three children, all under 10, so he might want to start scouting the locker room for future tutors in algebra.

Staying connected

If tabbing teammates for homework help seems unusual, consider bridging the generational divide at social functions.

The days before home games, families attended walk-throughs, with parents watching their adult children on the field. It would sometimes lead to awkward conversations.

"I had all these dads of all these players, they were all during my time so they were even huger fans of mine and had me take pictures with them and all that," Warren Moon said. "You almost felt like a celebrity on your own team, and it's not supposed to really be like that.

"You're supposed to be one of the guys on the team. So making sure you didn't get too far away from being connected with the guys was probably my biggest challenge."

This was difficult when players told stories in the locker room about having Moon's poster on their wall when they were in middle school. Now he was asking them to protect his blindside or catch his passes.

This forced Moon to become an ambassador of age. He'd find the bar his offensive linemen went to after practice and hung out. He stopped by position-group dinners weekly to stay involved. He catered lunches for players to show he cared.

In 1999, the first of his two years in Kansas City, Moon became close with Tony Gonzalez, the future Hall of Fame tight end who at that time was entering his third season. The two bonded over working route trees in warm-ups -- a routine Gonzalez continued throughout his career, which ended in 2013 at age 37.

"He ends up being one of my closest friends, if not my closest friend, on the team when he was 23 years old," Moon said. "And I was 42. Being around young people keeps you young, you know."

Brady also connects with his young teammates, from 28-year-old tight end Rob Gronkowski to 27-year-old running back Brandon Bolden, who is considered a close friend of the quarterback.

'He is the system'

Almost every quarterback who has played at age 40 or older has had to switch teams toward the end of his career.

Moon bounced between Minnesota, Seattle and Kansas City. Hasselbeck was in Tennessee and Indianapolis. Vinny Testaverde was in New York, Dallas, New England and Carolina; Doug Flutie in San Diego and New England. Brett Favre's late-career arc spanned Green Bay, New York and Minnesota. This meant picking up new offenses and understanding new schemes.

Brady won't have to do this. He's coming off one of his strongest seasons, winning his fifth Super Bowl ring after an all-time comeback in the title game and claiming his fourth Super Bowl MVP award.

Brady won't have to adjust to a new system.

"With Brady, there is no adjusting. He is the system in New England," said Gunther Cunningham, who coached Moon in Kansas City. "Warren changed teams a few times, you know, so there is a coaching level that goes on to teach him the system that he's under."

Teaching an old quarterback a new trick would likely lead to failure, so if a team was relying on a super-veteran, tailoring the offense to what the quarterback could do was paramount. Coaching was less critical than advising and listening.

"He's been there, done that," said Dan Reeves, who worked with a 40-year-old Steve DeBerg in Atlanta. "He's a guy that you want to pick his brain and let him do the things that he does well, but also take his advice when he’s looked at film and see what the other team has done well and also seeing, keep him invigorated by seeing, if there’s some new play, some new pattern or something, let’s work on it.

“Keep it as exciting for him as you possibly can.”

Ice cream and pajamas

Innovation is the key in how all players train and perform. Brady is the epitome of healthy dieting, using what he eats -- avocado ice cream -- as a way to make sure he's giving his body the most realistic fuel possible to keep him healthy and energized.

Brady is willing to try unconventional methods in order to sustain success. It's no different, though, than how other quarterbacks who played after age 40 took care of themselves -- minus the ice cream.

"They are on to something, on to something for them that maybe there's a healthier way to eat in-season, out-of-season, whatever," Hasselbeck said. "You're even seeing Brady finding a better way to recover, like a better way to sleep. He's got those pajamas he sleeps in that are recovery pajamas.

"I did the same thing with compression socks and Normatec compression boots. Compression and elevation became my life once I learned about it. It was something that every offseason I was trying to find something, a way to get better, a way to improve, a way to recover better."

Moon ate very little red meat later in his career and supplemented with more vegetables. He also avoided white sugars but couldn't see himself ever going as far as Brady has.

Taking time to let injuries heal, particularly in the offseason, was another vital component. Bodies don't heal as quickly at 40 as they do at 30 or 20, especially after years of hits. They trained harder than they ever had in the offseason to keep pace with their younger peers.

"As long as those guys stay away from major injuries, I think they'll be able to play as long as they want to," Moon said of Brady, Brees and Rodgers. "The legs are going to be the key. When your legs start to go, you better get out of the game because now you can't protect yourself anymore as far as danger, and now you can't move in the pocket like you need to.

"You don't have to scramble, but you have to be able to subtly move and be able to have the strength in your legs to be able to keep throwing the football."

Still seeking greatness

The decision to retire was clear to Hasselbeck and Moon. Eventually it could be to Brady, Brees and Rodgers. It often has little to do with on-field performance.

Moon knew going into his final season, when longer offseason training programs on-site were instituted, because he didn't want to keep commuting from Houston to Kansas City because it took time away from his family.

Hasselbeck moved around often late in his career and had promised his kids they would spend all of their high school years in one city. That, combined with an offer to become a broadcaster on ESPN, made the decision easier to walk away.

When a guy isn’t willing to go through the offseason training, isn't willing to put more punishment on his body or doesn't enjoy the day-to-day as much anymore, it's time to move on.

For Brady, at least, it's clear the passion still remains -- something Reeves heard about from his grand-nephew, New England center David Andrews.

"He texted me during the offseason and he said, 'Uncle Dan, you’re not going to believe who is here every day.' I said, 'Who is that?' He said, 'Tom Brady. He's here looking at film every day.' This is the offseason," Reeves said. "So there's no secret to why Tom Brady is successful. If he's doing that in the offseason, it's because he loves it. He is not tired of it.

"He still wants to be great and it's not the same old humdrum thing every time. He just wants to get better and better."

ESPN Patriots reporter Mike Reiss contributed to this report.