Absolutely. I don't exercise per se, but I live on the third floor, park at the edges of parking lots, and take walks at lunchtime if I can manage it. Even ten minutes a day will add up.
I would like to add: DANCING. Dancing is very intense, a lot of fun, and can be done in the privacy of your own home. Believe me, it's all I can do to keep going for 15 minutes, and that's only part of a CD. It's the most fun way I know to get some exercise in, and costs very little (and you probably have the stereo, the music channels on the TV, etc.)