Everything I teach in my exercise class can be done at home with no equipment. Here's just a few:

Aerobics:
1. RUN up and down the stairs. If you can't run, walk up and down as much as you can.
2. dance to your favorite music.

Weights:
1. lift cans of food, or bottles of water.
2. body weight resistance (lunges, squats, push-ups, sit-ups, etc.)
If you don't know proper form, get a good exercise book.

3. Balance exercises. Practice standing on one leg. Walk on the curb outside.

4. stretching.

These are the 4 cornerstones of a good workout program. If you watch TV, do it during commercials. If you're on the computer, take 5 minute workout breaks every hour. If you "forget", set a kitchen timer for one hour and exercise for 5 minutes when it dings. Then reset it!