Have a Ball with Fitness
You can do abs work, flexibility work or yoga, and simply sit around on the ball. Use the ball instead of a chair, and you'll strengthen your core without even having to think about it. If you want to get a little more advanced, then the best sources of instruction are DVDs or online demonstrations. Inflated exercise balls are not to be confused with medicine balls, which are smaller, weighted balls used for strength training and can contribute to a great, fun workout. Both balls got their start in physical therapy and rehabilitation, but you can incorporate them to increase strength.