Will power is NOT an infinite resource - every time we make a decision, we're draining a bit of the energy reserves we have available to make good choices. That's why at the end of a day of making great choices for ourselves (maybe), we feel exhausted and reach for the pizza and Netflix instead of the book and a salad. Here's a bit of the neurology behind it, and the BEST way to condition your mind into having superhuman will power and endurance.