Learning to strike somebody and learning how to take a strike are essential.
Being hit can really mess you up.
Clever self defence tactics and techniques may fall to pieces when you are actually taking hits.
It is imperative that you know how to relax and roll with the punch.
Developing your own striking ability is critical. Without it, you cannot hope to defend yourself.
You need to make each blow count.
Range, timing, distance, accuracy and penetration must be practiced relentlessly.
A bag or focus mitt is not the same as a person. You need to strike real people.
Do not pull your punches. Let them land. Feel whether or not you are receiving adverse feedback.
Learn to control your power, your commitment and your intent.
Punching thin air may train the body mechanics behind a strike but tells you nothing about your ability.