Joe Thornton has been around hockey his whole life. He's spent the last 22 years in the NHL.
Hockey is a grueling game, both mentally and physically. It can wear you down and will take its toll if you aren't careful.
The Sharks forward is now 40 years old and has learned the importance fitness plays both in being a productive hockey player, and in being in the best possible mental state.
"It took me a year or two to kind of realize, 'Hey, if I want to stick in this league, I need to be in top shape year-in and year-out," Thornton said as part of NBC Sports' documentary "HEADSTRONG: Mental Health and Sports. "It's become a 12-month a year job for me. I take a couple weeks off at the end of the year but then I am right back at it."
Once fitness became a habit for Thornton, it quickly turned into a way of life. He must go to the gym every day or else he won't be his best self. He recognizes the addiction to getting after it in the gym but knows it's vital to his overall mental health.
"I love coming to the gym," Thornton said. "It helps me -- also I get to work with trainers that are phenomenal. Mike Potenza, I love coming to the gym and working with this guy, To me it's fun. I enjoy it. I enjoy coming in every day, putting some music on, hitting some weights and feeling good about myself. If I don't do that every day then I just don't feel the same.
"I know I'm addicted to the gym. I love getting the sweat in. I love the camaraderie up at the gym. It's a big part of who I am now."
Being in peak physical shape has helped Thornton be a fixture in the NHL for two decades, scoring 413 goals and amassing 1,484 points.
As physical a game as hockey is, the mental aspect of the game is even more important. Being in shape and knowing he's put in the work in the gym, puts Thornton in the proper mental space to succeed on the ice.
"Hockey is such a mental game," Thornton said. "It's like all the major sports, golf, tennis. It's major mentally and I think the healthier you come in, the stronger you come in, you are just mentally stronger. I truly believe that you have an edge on the competition. You are in peak shape. You feel good, you feel strong and nothing can stop you at that point."
[RELATED: Watch all of the vignettes from HEADSTRONG]
You can watch all of the "HEADSTRONG: Mental Health and Sports" vignettes right here. The full documentary will be playing all month on NBC Sports Bay Area and NBC Sports California.
Check our channel listings page for times and dates.