I get tunnel vision when I've been coding for several hours. I'll be stuck on a problem and I'll keep switching back to the same two areas of focus that I've already exhausted. I'll get frustrated because the problem seems totally inexplicable. The other day I was stuck on such a problem at 8pm. My sister in law suggested I just go to sleep, and look at the problem with fresh eyes tomorrow. Doing what she said, I solved the (stupidly simple) problem within 5 minutes of turning my laptop on the next day.

There are SO MANY environmental and physiological factors which go into your state of mind. Some variables that I try to control for:

1. What (if anything) did you eat today

2. How much water did you drink

3. Did you shower today

4. How much sleep did you get, or how long have you been awake (probably the most important one right here)

5. What is the warmth of the light where you are working (is it cloudy and rainy outside?)

6. What is the temperature of the room

7. Is anything else going on in your life occupying your mind right now? If you take medication: did you take your medications?

8. Did you exercise today? Do you exercise at all? Are you healthy?

9. How is your posture?

10. Is your work environment clean? Is it noisy?

11. Do you work better with music on, or in silence?

12. Did you drink so much caffeine that you are now manic and can't focus?

13. Are you happy?

The brain is a part of the body