Watch Now: Concern Level: James Conner (0:51)

Curtis Martin's decorated career as an NFL running back earned him a place in the Pro Football Hall of Fame. A five-time Pro Bowler during his time with the New England Patriots and New York Jets, Martin helped the Patriots advance to the Super Bowl a year after winning Offensive Rookie of the Year. Two years later, Martin helped the Jets advance to within a game of the Super Bowl. 

Perhaps Martin's most impressive career accomplishment took place in 2004, when at age 31 he became the oldest player in league history to win the rushing title. This week, Martin revealed that he played the majority of that season with a serious MCL tear

"My MCL had almost a grade 3 tear in it," Martin told Tim Benz of the Pittsburgh Tribune-Review. "It was so loose. I played with it from I believe the sixth or seventh game throughout the rest of the season. At the time, the doctors were telling me that I needed to sit out and let it rest and I may need surgery." 

Unsure of whether or not he should continue to play, Martin said he reached out to Bill Parcells, who at the time was in his second season as the Dallas Cowboys' head coach. Martin spent two seasons with Parcells in New England before spending two more years with him in New York. 

"I said, 'Coach, look, this thing is really bothering me. It feels wobbly, like I don't even feel stable on it. What do you think I should do?' I said, 'I think I can bear the pain, it's not the pain, it's just whether or not it's best for me.'

"He said, 'Well, you know Boy Wonder, I always think that you should take care of your body, take care of yourself. I think that's your priority and that's what you should do because you never know how it will effect you longterm. But on the other hand, you never really wanna come out of the huddle because you never know who who's going into the huddle.' And that just stuck with me forever. He had told me something similar to that when I was a rookie, and so it's always been my passion that no one else should ever get in that huddle."

After taking the advice of his former coach, Martin decided to continue playing. Despite the pain, Martin led the NFL in carries (371) and rushing yards (1,697) while averaging a career-best 4.6 yards per carry. He also rushed for 12 scores while helping lead the Jets to a playoff berth. 

In the first round of the playoffs, Martin's 113 all-purpose yards helped New York pull off an upset over Drew Brees, LaDainian Tomlinson and the rest of the Chargers. Martin was just as effective the following week against the Steelers, rushing for 77 yards on 19 carries while catching four passes for 29 yards. And if not for two missed field goals, Martin and the Jets would have upset the Steelers, who went 15-1 during the regular season. 

In 2005, Martin suffered another knee injury in Week 2 of the regular season. While he played through the injury for nearly three months, Martin ultimately decided to undergo surgery on his MCL after 12 games. Martin retired the ensuing offseason as the fourth leading rusher in league history. 

Despite his success as a running back, Martin was often overlooked during his career, as he played in an era that featured various other star running backs that included Tomlinson, Terrell Davis, Emmitt Smith, Barry Sanders, Edgerrin James, and Jerome Bettis, among others. Martin was actually traded from the Patriots to the Jets after an injury sidelined him during New England's final four games of the 1997 season. Martin used his doubters -- along with the fact that he was overlooked -- as fuel for his fire, as he became the second player in NFL history to rush for over 1,000 yards in 10 straight seasons

Speaking of running backs dealing with doubters and injuries, Martin was asked to offer some advice to Steelers running back James Conner, who is entering the final season of his rookie contract. A 2018 Pro Bowler, Conner is coming off a season that saw him miss six games due to injury. 

"One thing that I've learned about the criticism is that you can never really control it," Martin said. "One of the practices that I've implemented in my life is learning how to not allow what I can't control to affect me. That would definitely be my one piece of advice. ... I think there's a healthiness to understanding how people think, but I think it becomes detrimental to yourself when you allow it to enforce your own mindset and the way and how you do things. So I would definitely say to block the noise out. That is the most important." 

"On the other hand, do what's best for your body, and keep in mind that you always wanna be on the field when you're a professional athlete."