The energy demands of exercise require support from every major system in the body. Your heart, lungs, bones and brain are engaged. The positive effects of regular exercise strengthen your endocrine and immune systems, reduce stress, combat arthritis and obesity, and help you sleep better. It is also associated with lower risk of cancer, diabetes, cardiovascular disease and other ailments. No medication or other treatment can come close to the whole-body benefits of regular exercise, especially when combined with other healthful lifestyle choices.