Bas Rutten says “everything hard” meaning every kick or punch needs to be hard no taps or tickles. Starting with the basics body body head combo, it works in forcing the target to drop their hands to protect the body so now the head shot is open. The issue I see in gyms around the way is that everyone thinks that you can just feint to body shots and the head will suddenly become free for assault. Not the case stop thinking that way there has to be a reason that they drop their hands either a solid body kick or a soul separating hook to the body and then the hands come down, but any variation will do as long as power is the focus.
If you don’t hit hard it’s because you either haven’t trained hard enough so you don’t realize what hitting hard really is. Or you may not have the cardio to hit hard for a full round or a full fight. One is an easy fix you go look up the Bas Rutten Workouts and then you will understand what training power on the bag really is. (Oh look at that the links right here surprise https://www.youtube.com/watch?v=qtLqcZi-_ds ). On the other hand working hard enough is is a personal struggle either you will or you won’t nobody can force it out of you because only you know if you’re really working hard or if you merely putting on airs.