Earlier this summer, NBA legend Tim Duncan decided to call it a day on his storied career. After such a long time at the highest level of athletic competition, it may take the 40-year-old some time to adapt to a different routine.

The former San Antonio Spurs big man is struggling to get used to his new way of life and still feels the need to stay in shape according to his former teammate Bruce Bowen.

Bowen spoke to DeAntae Prince of SI.com recently, describing Duncan’s post-retirement mindset.

“Last week, (Duncan) picked me up from the airport and we're talking, and he's stressing that he needs to start working out.”

“Those (pounds) start adding up, and the athlete in him says ‘I can't be this big or I can't be this heavy’, and I don't see him as heavy. You look at his frame and it's not there, but when you're accustomed to doing things a certain way you can feel yourself expanding.”

As a fellow retiree, Bowen sympathises with Duncan and says that even at the age of 45, he still feels a sense of paranoia regarding his naturally declining fitness.

“It's one of those things that kicks in even now. You feel your waist expanding or your belly getting out there, and you're like, ‘Oh, I got to do some sit-ups, I got to go run, I need to something,' because we've worked out for so many years. And while you don't want to do it to that degree, at the same time you want to make sure you keep your body right.”

There has been much speculation surrounding Duncan’s next move after retirement; it seems that whatever the move is, it won’t be a particularly unhealthy one.