I consider myself to be pretty fit. I run on my elliptical machine for twenty minutes a few time a week, I hike up to the top of a small mountain just about everyday, and I go for long walks whenever I can. Lately, though, muscles have been feeling stiff. They don't hurt. They just don't want to stretch. I think I eat OK. I get enough protein, I'm always eating fruits and veggies, and beans are always on the menu. Any ideas?