lol, I do run on the balls of my feet, well you push off from them anyways, gives you more umpf (it should be a word) I have never had any cross fit training ergo the exercises would be more dangerous for me to try and get into, kettle bells aren't something to play around with without an instructor fyi for anyone interested in crossfit. That is until you get used to it then go for it, if it's what makes you happy.