For individuals who are exercising for the prevention of osteoporosis, resistance exercise is a bit more important than aerobic exercise. In order to affect bone density, weight must be placed on the joint in order to make them stronger. So for them, resistance exercise must be performed regularly and if aerobic exercise is one of the preferences, it needs to be a form of exercise that is weight bearing, such as walking. The first and most important thing is for people to understand the benefits that can be gained from a regular exercise program. The other thing that's very important is to choose an exercise to start with that will minimize the risks for injury.
Most people quit an exercise program because they either injure themselves or are bored.
The other thing that's important is setting goals and objectives, and making these goals and objectives realistic. You need to have fun and enjoy what you do. It's also important to make time for the exercise. This often requires people to shift their schedules significantly. If you already have a very full day, it will be difficult to fit exercise in.