Sometimes workouts are hard – like really, painfully, I’m-going-to-throw-up-or-pass-out-or-have-a-heart-attack hard. During such times, we have a choice: give up or keep moving. I prefer the latter. There’s something invigorating about pushing through the pain. It’s exciting and almost strengthening. But why? What is it that causes me to feel a surge of energy whenever I …
