It should not hurt to stay in shape if you always warm up before your exercise session. How do you do that? It is simple. Walk for at least 5 minutes and perform gentle stretching exercises. This helps prevent injuries and prepares your body for more strenuous effort. After the session, cool down with another 5 to 10 minutes of slow walking and gentle stretching to help prevent stiffness in the arms, back and legs and to aid re-circulation.