The gym on-campus is actually very reasonable, but that's just not a luxury we're willing to pay for right now.
My solution has been fitness DVDs.
I checked a few out from the library, I dug out a pilates one from a drawer, I borrowed from friends.
Here is what I like about this exercise option:
1. The variety keeps things interesting and has helped me figure out what I do and don't enjoy.
2. I can exercise in my pj's.
3. My living room is never crowded with people trying to use different machines.
4. Baby Girl can nap or play in the exersaucer while I get fit.
5. Occasionally one might be able to convince one's husband to participate in something like Fit Pregnancy: Get your body back after baby, if one's husband is a very good sport and very sure in his manhood.
6. It's cheap! I have yet to buy a DVD (save the pilates one I bought several years ago).
For other frugal tips check out Frugal Friday over at Biblical Womanhood.