For those of us who loathe excercise for the sake of excercise, may I suggest metalworking? You get the distraction of a project / learning to make cool things and it's a surprisingly physical process to inflict your will on such dense objects.
rock climbing in an indoor gym is safe and low impact and programmers often enjoy the mental aspect of it. it incentivizes you strongly to keep weight down as well.
* There's a point--learning how to use your body/leverage.
* It's social. There will be fellows to motivate you to train consistently. You might even make a few friends.
* There's progression. Whether belts, tournaments, or just being about to beat your training partners improvement is pretty noticeable.
A gym membership is ~$100-200/mo. There are bad gyms. Make sure not to commit too early and try others if you don't like the environment.