How do exercise?

[Vicious_Unicycle]

  I've never been very athletic. I was on the cross country team in high school, but that was a few years ago and even then I was pretty bad at it. I essentially stopped exercising altogether after that. Recently I started going for walks regularly, since that was about all the exercise I could handle. I'm interested in trying to get in better shape, but I don't know the first thing about working out and everything online seems to be targeted either towards athletes/bodybuilders or towards people who want to lose weight. I need to find an approach that's appropriate for my specific goals and limits.

  At this point my most pressing concern is the fact that most of my left side is substantially weaker than my right side, to the point that it's causing me a lot of discomfort, sometimes even pain. If I can get that taken care of, I think I'd like to work on more general fitness stuff. But at the moment that would just make the problem worse, since my right side would inevitably end up doing most of the work.

  Anyway, I really like the attitude this site has towards fitness and I think it will make exercising seem a whole lot less daunting.