I feel I can personally relate to your situation up to a certain degree. Six years ago I broke my acetabulum (Hip) in a motocross accident. Being sort of an adrenaline junkie myself and to hold a promise not to ride cross anymore. Airsoft has replaced that gape, Filled that whole.
I do feel the same after pushing myself from a game. Sometimes the next day I'm bed ridden. Never has the thought come across to not push myself so hard or not attend or pass up a good game.
The only events I have pass up on are the ones I know I would not be able to be of help to my team / hinder the completion of their objectives that day.
Sometimes I wish I would be in better shape for the sole reason to be able to stick around post game and shoot the shit some more...hang out. Have a beer in some cases. Sharing a days glorious moments with fellow airsoft'er is sometimes dificult because I must retire early to minimize the next days suffering.
Most players who know me are aware that my condition in no way hinders my "lethality" in-game. Actually sometimes I think I gives me a minor edge in situation where patients is necessary (sniping & ambushes).
So I to salute *salutes* you for holding onto what you are passionate about.