Runners?

[Aquattro]

I'd start with a learn to run clinic, which trains with a walk/run interval. One you can run more than walk, start on some longer runs, say 5k. When you can run that with relative ease, start adding 5 or 10% a week. I run on an empty stomach first thing in the morning, but eat well after the run. I trained a woman last year that was 20 or so pounds overweight, and day one she couldn't finish a k, after a month, 10k in under 60 minutes.

Make sure you get rest days in, eat well, and if you're older, don't push too hard through pain.

But I would certainly recommend a clinic at your local running store, the group atmosphere will provide motivation, and you can get all your questions answered.