This is very misguided advice.<p>Long bouts of endurance exercise can be very taxing and destructive to many body parts.<p>Exercise as a whole can be done efficiently and effectively without wearing your body out.<p>Anaerobic exercise (lifting weights) can improve collagen and muscle production via several hormonal pathways. These same pathways tend to have negative feedbacks from excess aerobic exercise (i.e. high cortisol, low GH output in distance athletes).