I also want to release stress, I felt so relieved to actually hit something. The pain reminds me to not be lazy. I don't know how to explain it. It's a motivator more then anything. I have trouble motivating myself to try harder.
Plus your actually using force.
I felt so much more calm coming home I really want a outlet for stress relief and this was amazing. Nothing else mattered once I was in there training. Work all of that did not matter.