i'm much to young to feel this old!

I'm EXHAUSTED! I don't know why I'm so tired--I'm almost beginning to think that I've caught Mono. It could be the heat, the long days at work, and the lack of exercise, but no matter what it is, I can't seem to shake it. Since I haven't been exercising regularly, I went hiking after work. Initially, I went letterboxing, but when I couldn't find box number two, and it began getting close to 8pm, I just started trying to find my way back to my car. Two hours of hiking--it was fun, but I was so dehydrated that I almost passed out at Walmart while standing in line. People in Richmond are so damn active ALL the time! I don't get it--they're always running, hiking, walking, biking, skating, playing tennis, basketball, whatever! People in Michigan aren't like that! Where do these people get the energy? And where can I buy some?