my last fight i was sick as a dog...i broke a fever that day maybe 3 hours before the fight. i went thinking i will bow out and get better. but once at the venue, i got the urge to fight. yeah i was sick, and tired but well wtf i just had to go for it as for your old age, unless you can say 40 and mean it please don't mention it again. you can hang tuff with some injuries, but as a boxer the hands,wrists and back are ones that can cause long term problems...so watch these and remember most likely if you are hurting and your opponent is a serious boxer they are also not in prime shape. most combat athletes compete with injuries or at the very least not being 100% ...but always step back and consider what will this do to you in the long run? and what in the short term.. better to heal as much a spossible, but let some things go as they are. hope this helps