Yes, you should forget about it.
1) I don't know if you've been following the news lately, but we're in a couple of wars, a couple of relief efforts, and of course we are dealing with the neverending string of our own national disasters. National guard gets called up for ALL of that. You'd be looking at at least one and maybe two deployments on a 4 year contract. Honesty I can't see why anyone would join the reserves at this point, even if they're not looking at medical school. After all, if you know you're going to be spending a lot of time active duty anyway why not just go active duty and get the full benifits.
2) You don't get 'weekends' in medical school. For the first 2 years you will need at least some of them and probably almost all of them to study, for the second 2 years you will often be expected to work through the weekend, no excuses.
3) The military is not a summer camp and nothing they will make you do is something you would voluntarily do to recreate. If you want to run around shooting guns and camping out I recommend either hunting or a hardcore paintball team. Your job in the reserves will be a combination office drone, janitor, scut monkey, and occasionally you will get the chance to drill on the most miserable and mindnumbing parts of warfighting.
In any event, if you want to join the military, the military desperately needs doctors. Look into FAP or HPSP.