We are what we do in life, so its only common sense if you want a hard punch you should practice punching ,a lot.
Do you think that Tyson or any other of the great boxers of our time were like that with luck .No they honed their skill every day of their lives.
This technique here may look like a lucky punch but a well aimed overhand right can stop a fight with one hit.
Practice this when someone is throwing a lazy jab and you will see what I mean.
Like I said in the video still practice all your other punches I believe this is well worth adding to your arsenal.