When you're chasing a big goal, you're supposed to feel good a third of the time, okay a third of the time, and crappy a third of the time. If the ratio is off and you feel good all the time, then you're not pushing yourself enough. Likewise, if you feel bad all the time, then you might be fatigued and need to dial things back.

Learning the Rule of Thirds was life-changing for me as a person in general, because it made me believe in the days that didn't feel great. In fact, I relished them.