I'm 51, so I guess I'm at the top of the downhill slope.
I have two 62# bows, a longbow and a recurve. I shoot both during the summer, but once it gets close to October, I go with my 56# Foley recurve. Practicing with the heavier poundage makes the 56# bow feel great.
I do try to stay in shape year round, always with shooting my bow in mind. Lately I've been shooting very little, but working out a lot. I have to say though that nothing beats shooting your bow for keeping those important muscles strong.