I'm 6'5" and ~ 290lbs,...yeah I have a gut, but I still consider myself to be in pretty good shape. My job, (nurse) requires me to lift some pretty hefty people sometimes. I've have them as heavy as 550lbs, but never have really hit my limit on being able to do what I need to do for them. (ie, move them from one bed to another, assist them in walking etc...)
I guess if you feel good and can do everything that you want to do when you want to do it, you're in good enough shape.