There is not much that feels “healthy” about limping down the stairs after leg day. Or climbing out of bed at 5:00 a.m. to swim when the rest of the world is still asleep. Or pushing through the final miles of a long run when your legs are heavy, your lungs are burning, and your mind is begging for relief. And there is definitely nothing comfortable about racing at your limit over long periods. Especially the longer the distance gets.