Get Your Heart in Shape
Jogging, swimming, bicycling, working out on a machine such as a cross-country ski machine, stair stepper or elliptical trainer, dancing (but not to slow dances like the fox trot), aerobics classes… All work great! Just note that if you want to improve the state of your bones as you improve the state of your heart, you have to be standing as you exercise.
Bicycling and swimming are great for the heart but will not make the bones denser. Some women prefer cross training: walking or jogging some days and swimming on others. That allows for great full-body workouts. Swimming, for instance, works the muscles in the arms in a way that walking does not.