For kickboxing and muay thai, this seems to be the one thing about the kick that troubles me the most. I used to train shotokan karate, and kicks would always have the supporting leg flat footed and firmly rooted during the kick. It's been ingrained in my muscle memory for any kind of kick and now it's messing me up during my round kicks in kickboxing and muay thai. What tricks, drills can I use to help me get up on the toes for better rotation?