It's no wonder that when we are mentally drained we struggle with complex problems and self-control, opting for cartoons and cookies instead. - Brad Stulberg

IS FATIGUE ALL IN YOUR HEAD? In the early 1990s, in a physiology lab at the University of Cape Town in South Africa, an exercise scientist named Tim Noakes, MD, unveiled a radical new way to think about fatigue. Until then, prevailing wisdom held that fatigue occurred in the body. At a certain intensity or duration of physical effort, the demands we put on our muscles become too great and, eventually, our muscles fail. Ask any athlete, from a marathon runner to a powerlifter, and they will be familiar with the feeling. It's not a particularly comfortable one. What at first is a manageable burn becomes worse and worse until they can no longer bear it. The runner's pace slows to a mere shuffle; the powerlifter can't manage to hoist the barbell up for one last rep. Try as they might, they simply run out of gas and their muscles cease to contract. Noakes, however, wasn't convinced that fatigue occurred in the body or that muscles actually ran out of gas. He questioned why so many athletes, seemingly overwhelmed by fatigue, were suddenly able to speed up during the final stretch of a race when the end was in sight. If the muscles were truly dead, Noakes hypothesized, these finish-line spurts would be impossible. To prove his point, Noakes attached electrical sensors to athletes and then instructed them to lift weights with their legs until they simply couldn't lift any longer. (In exercise science, this is called "inducing muscle failure.") When the weights slammed down and each participant tapped out, reporting they could no longer contract their muscles, Noakes ran an electrical current through the sensor. Much to the surprise of everyone — especially to the participants whose legs were dead — their muscles contracted. Although the participants could not contract their muscles on their own, Noakes proved that their muscles actually had more to give. The participants felt drained, but empirically, their muscles were not. Noakes repeated similar versions of this experime

The good news is that just like the body, by stressing and allowing the mind to recover it also becomes stronger. Scientists have discovered that the more we resist temptation, think deeply, or focus intensely, the better we become at doing so.

Excitement temporarily feels good. And there is no doubt that bursts of excitement add texture to your life. But if you are obsessively trying to generate the feeling, you may miss out on what is in front of you because you are already moving ahead.