For me, food effects my intelligence in massive ways. Caffeine is the devil, murders my IQ, reduces my vision, gives me insane anxiety, its just god awful.
If I dont eat breakfast It slows me down significantly, and since I keep stats of my work, its roughly 20% reduction, but can be as much as 70%, which means when I eat right and avoid caffeine, I can literally do more than twice as much than if I dont eat and have a cup of Joe.
On a bad day, 50 files, on a good day 180. Caffeine messes with me so much, It reduces my performance more than the flu.
Being surrounded by people who are vindictive really effects my ability to put energy into learning. People like that are such wastes of oxygen. Stress from illogical people increases cortisol in the brain, which causes damage over time.