I agree with Standalone. But although your bike may not be the most exotic brand, it doesn't mean your goal for it should be put aside. Being someone that also enjoys bringing old bikes back to life, I'd say rearrange your plan.

Perhaps this way:

Wave 1: Sand/clean and refinish any rusty spots, repaint(?) -but there's nothing wrong with this current paint job, anything else I think of (all FREE things you can do for your bike for aesthetics, proper and safe function, and anything for it to ride better than it currently does). Oil the bike, check the brakes n all cables too. Dial in the bike (get the most comfortable adjustments done. like the seat height and the stem length/ height, etc etc. So far, this should cost you NOTHING! =)

Wave 2: 2 new tires, a new chain(or oil the old one), 2 new inner tubes (Craigslist will almost always have parts that are 'good enough' for your purpose) -you'll save more this way. This may cost anywhere from $30 to $50 if you're looking to save.

Wave 3: Rear rack (pricey but they last as long as you take care of them) and maybe bags (or a back pack or messenger bag will be cheaper), lighting (craigslist, again).

Also, have you entertained this Q:

-What kind of terrain will the bike mostly be rolling on?
If the terrain is not too hilly, perhaps a single-speed project can help you reach your goal to increase exercise and therefore reach a better state of health. Besides, the maintenance is SO MUCH EASIER AS A SS.

just my .02 cents. But would like to see your progress if you're able to post pics and such. You have a good basis for your build and aim. It could take anywhere from a full week or 2 or 3. Sounds like fun! -GOOD LUCK! =)