Muscle memory

"I fear not the man who has practiced 10,000 kicks once, but I fear the man who has practiced one kick 10,000 times."
--Bruce Lee

Again...practice practice practice. Develop good habits and good muscle memory. It will serve you well in time of need.
Muscle memory is simply a habit, a reflex you develop. Similar to being able to keep your balance when riding your bike. It was not always so. When you first tried riding a 2 wheeler as a child, you probably fell often. Then you developed that balance, that sense that you are in control of the bike, not the reverse. To properly defend yourself you need to develop appropriate muscle memory as to respond quickly, without even thinking.