Yard Work and the Brain

Clipping saplings and overgrown weeds in my yard has a strange effect on me and it has happened twice. I like using the loppers and feel productive doing the work but I've noticed it makes me angry and full of adrenaline, I want to fight and scream! Is it something about this particular gesture that says "fight" to my brain? Or maybe I am only attracted to doing yard work when I am agitated.