Active duty military here. I spent 3 years in a reserve unit.
(fitness, guns, tactical training, etc)
If this is what you think you will be doing on weekends, then you are wrong. Your drill weekends will consist largely of powerpoint training presentations regarding alcohol abuse, sexual harrassment prevention, and other things that the politicians have decided that the troops need. Very little time for fitness, guns and tactics. Fitness is your responsibility and really is on your time, while the guns and tactics is saved for your 2 weeks or more of training. And yes, guard troops are deploying to Afghanistan.
There are other good, compelling reasons to join the Guard or Reserves, but not these. Talk to the recruiter, and if you already have a degree, don't commit to anything less than OCS, unless you find a specific field you really want to spend time working in.