portion size is overlooked too,,,,, keep it small, dont eat till your full.. if u can stomache it, sip green tea all day
being inactive you could get by on eating very little... theres always a way to get some kind of training in.. u could train upper body only till the knee feels better, u could swim, fuck the missus for hrs each night etc etc etc..
look for a positive.. theres been times where ive been so fucked ive just done calves 3 times a week, a little of somthings better than nothing at all