Want to exercise without spending a lot of money? If you're self-motivated and don't have health problems like a touchy back or a heart condition, consider working out at home. I've worked out at home for years and prefer it to going to a gym. When you work out at home, there are no dues, no commute, no public shower, and no pressure to buy expensive workout clothes and puffy, high-tech shoes. I exercise barefoot in the summer and in basic canvas tennis shoes in the winter. I work out on my own schedule to my own music or enjoy the quiet. There's no pressure to keep up with others.
I use Fred Hahn’s Slow Burn method of weightlifting (see Exercise without Joint Pain). All I need are four sets of free weights, a yoga mat, a fan, a timer and a metronome. The last two items are free online (links are in the Exercise without Joint Pain post). I do this workout twice a week.
Keep safety in mind, especially if you work out alone. Get familiar with any machines you use so you don’t, for instance, do a face plant on your treadmill. My dog loves the treadmill, and accidentally got on from the front once. If she hadn’t been quick enough to jump off, she’d have been conveyed smack into the door. Weightlifting can be hazardous, too. When I was in an engineering design class, one group designed a device to lift a bench press barbell so that the weightlifter wouldn’t need a spotter. The discussion moved to the on-off switch, and a wiseguy in the class suggested the Clapper. Kidding aside, an acquaintance believes that she ruined her knee doing aerobics (which included pivoting on her foot) on a carpeted floor, which twisted her knee. If your workout involves pivoting on your foot, I suggest using a hard, smooth floor and dance shoes, ballet slippers or sueded tennis shoes. Your knee isn’t meant to be torqued. And if you're bouncing around, trust a dancer on this: you need padded shoes AND good landing technique, although even that might not be enough to prevent injuries.
Cardio exercise is fine if you enjoy it, but I haven't observed it to be a good means of weight loss. A recent study bears this out. I've taken cardio classes, and I've been a swing dancer for eight years. I can't think of one person in either scene who slimmed down; I can think of a few who gained weight. (See my posts on weight loss if that's what you're interested in.)
Common sense suggests starting out moderately to learn what your limits are, then building in intensity. Think about progress, not perfection.