I remember well when I was in my fifties I could work the college athletes who hired on for the summer under the table. At 69 I can't do that any more, and the aches and pains are real, mostly the result of accumulated orthopedic damage from 50 years of construction. Surgery has corrected some of the damage, some I just have to live with. Developing your pain tolerance will help you keep your youth. A lot of people stop moving when it hurts, which only makes it hurt worse;)