But, as he prepares to face Toulouse in Sunday's European Cup semi-final at the Walkers Stadium, the 36-year-old Leicester player insists he is as mentally and physically sharp as he has ever been.
"I wouldn't be doing this if I didn't enjoy it," said Back, whose career will come to an end after the forthcoming Lions tour to New Zealand.
"In terms of my enthusiasm and desire to achieve things it's as strong as ever, it's probably a bit stronger in fact because I know it's my last playing season.
"Whenever I play my last game for Leicester this year and my last game for the Lions, that's it for competitive rugby, so I suppose every game is a bit more special."
Back is in the twilight of his playing career and it would be entirely natural for him to be subconsciously taking his foot of the gas as his prepares for his future incarnation as part of Leicester's full-time coaching team.
But that is what has marked Back out throughout his long and illustrious career - his determination to do things differently and as close to perfection as possible.
At 5ft 10in tall and close to 14 stone, Back initially spent much of his time trying to convince doubters like former England coach Jack Rowell that he was big enough to play rugby at the highest level.
It seems incredible now that anyone could have questioned Back's credentials, but throughout his career the 66 times capped openside has had the sense that he has had something to prove.
"I've approached every game in my career the same," he explains. "When I was a five year old I wanted to win and that hasn't changed."