I live in Saint John, New Brunswick Canada. I used to love riding my bicycle as a child. We drove all over the community, to the store, across the ferry, back and forth to school. Bike riding kept us healthy, and making new friends as a child. It is sad today that a lot of children have traded this great form of exercise in for some kind of electronic device or computer. As an adult I realize bike-riding offers many benefits for the body, as well as for the mind.
Bicycling is a good cardiovascular exercise that could increase the health of your heart. Bikes come in many speeds and options today. This will allow you to increase your fitness level as your cardiovascular function improves. One of the things I have found is bicycle shorts with the padding in them (a must) is something you need the older you get. Not only that, I would not recommend a bike without shocks (sometime I will do a separate topic on this). If you have not bicycled for a while start off easy. Take it in progressive steps.
Bicycling is kind to the joints, and you can enjoy the great outdoors at the same time. As we get older we experience joint pain especially in the knees, or at least I have. Osteoporosis causes joint problems to worsen because of the lack of proper calcium levels in the bones. The aerobic benefit is comparable to jogging or running without the strain, and impact. Make sure the seat height on your bike is adjusted to allow your legs full range of motion with each revolution. Full range of motion also promotes better circulation to the lower extremities, which do the majority of the work in moving the bicycle. It's also great way to release your stress from daily work either if you work at home or have a regular job, in fact I often back to and from work.