Consistent excercise increases the number of (saratonin?) receptors in the brain and (saratonin?) is what is given off by the brain when you feel pleasure.(and "pleasure" doesn't immediatly mean something dirty, anything that makes you happy triggers (saratonin?)).
I always feel good and ready for anything after a good training session though I wouldn't say I'm more creative afterwards, I get my good ideas while on the toilet or in the shower.
Too those who always dreamt too big, went too far, worked too hard and found their own way... I salute you.