Try tracking for a day how many decisions you make in 24 hours. You make small ones regarding what to wear, eat, or watch on television. Then there are some larger ones you have to make. Then there are those that may be small but turn into bigger-than-life decisions.
Today I was stuck in a non-stop meeting loop. The meeting loop gave me a migraine and a half. Part of the headache was due to having to make one quick decision after another. Unlike some meetings, today I was deep into conversations where one decision after another had to be done on the spot. And, at times I just felt depleted. The brain should only be taxed so much.