Fatigue

"'the sense of fatigue is often a very fallacious index of the working capacity of the body … there is not necessarily any correspondence between the subjective feelings of fatigue and the capacity of the muscles to perform work'"

"'People who don't see you every day have a hard time understanding how on some days‒good days‒you can run three miles, but can barely walk across the parking lot on other days,' [my mom] said quietly."