But when it comes to the crunch, the 35-year-old Dunedin Technical central defender finds a way to escape any previous promises.
He had an opportunity to throw in the towel towards the end of last season when he broke his nose.
He probably should have called it quits when he fractured a bone in his leg during an early exchange in the last game last year.
Instead, he played on before eventually hobbling off about 10min into the second half.
And, earlier this winter, he was involved in a sickening head clash and missed four games while he recovered from a concussion.
''Each one of those should have been my last game,'' he said with a chuckle.
His wife, Jenny, shrugs when he tells her ''this is my last''.
The couple have two children, Zachary (3) and Arabella (6 months), and Douglas, a chartered accountant, leads the Risk Assurance practice for Dunedin at Pricewaterhouse Coopers.
They have busy lives but living in Dunedin has helped him put off retiring from the game he loves.
''That is one of the fortunate things of coming back to Dunedin, where you really do live five minutes from where you work and football practice is just five minutes from your house,'' he said.
''And I have a very patient wife. Every year I tell her it is going to be my last season. Now she just laughs and shrugs. But even though every year I say this is my last, I think this possibly is.''
Douglas started out with Dunedin Technical when he was 21. He had four seasons with the club before moving to Wellington and then London.
He has been back in the city three years.
Caversham has already wrapped up the league this season but Dunedin Technical still has plenty to play for.
It is unbeaten in its past 15 games and will host a Chatham Cup quarterfinal against Mangere United at the Caledonian Ground on Sunday.
Dunedin Technical has a proud record in the knockout competition, and won the Chatham Cup in 1999.
Player-coach Aaron Burgess and midfielder Justin Flaws both scored during that final and 16 years later are still with the club.
Burgess starts from the bench while Flaws is a pivotal player in the middle of the park.
''Just knowing they are there makes everyone else feel more comfortable,'' Douglas said.
Douglas has been in good form himself.
His primary role is to shut down any attacking forays but he is a strong aerial player and has banged in 11 goals this season - most of them with his head.
''There have been a few off the foot which has surprised people,'' he said.
He needs one more goal to beat his previous season high.
He is hoping it will come against Mangere United, a team Douglas admitted Technical did not know much about.
''It is all through talking to a few guys up north but we do know they have at least a few good players. They have a bit of talent in their team in the key positions in terms of literally one good player up front, in the middle and at the back which pull the side together.''
However, Mangere had had more competitive games in the Cup and that could prove to be an advantage, Douglas said.
''If you play tough matches going into these [fixtures], you are better prepared. There is no doubt about that.
''They are sitting in the middle of division one in their actual league and you wonder what these guys have got. But then you see how they have gone in the Chatham Cup and obviously it says they can turn it on when they need to. That is what the Cup is all about.''
