Lots and lots of water.
I've been outside and active my whole life and people always ask me how i still feel so good after 20 miles on the trail with a backpack or working in a recieving room moving boxes for a 10 hour shift or riding long distances, and the only thing I can figure out is the fact that I drink loads of water a day. When I started having to drink coffee to wake up before shifts at work and didnt drink much water I felt like hell the following morning/couple days, especially my knees, ankles and shoulders (I have some bad joints from climbing and stuff). Granted I'm considerably younger, but I think often times people overlook the smaller measures that help maintain good health. Lots of water before during and after you do strenuous activity.