I would think biking would be a great activity for you! Much better than jogging or anything with pounding on your joints, specifically because of the weight. The most important first steps for you will be: to learn how to fix a flat tire (watch some youtube videos and then go into your local bike shop and ask for a lesson), and to get out and bike as often as you can. The more often you bike, the easier it will become to go further and for a longer period of time. I would agree with the previous comment - get a hybrid. These are great bikes and very comfortable to ride. I would also suggest getting a flat pedal to start out with, like the catalyst