your mitochondria contribute more energy to your brain’s performance than your heart, lungs, or legs. Your brain gets first dibs on mitochondrial energy, and your eyes and heart are right behind it in line.
The first symptom that your mitochondria are overtaxed is fatigue. Fatigue is an absolute performance killer. It causes cravings, moodiness, brain fog, forgetfulness, and lack of focus.
Our fight-or-flight response kept us a little bit distracted all of the time so that we could constantly scan the environment around us for threats. When our brains perceived a threat, they would divert all of our energy into the systems necessary to either kill a lion or at least run away from it faster than the slowest member of the tribe. The problem is not only that lions don’t pose much of a threat anymore but also that our bodies can’t distinguish between real and perceived threats—they react the same way to any stimulus
Every time you resist an urge, you are making a decision. Scientists have proven that there are a limited number of decisions you can make each day before you reach “decision fatigue.”