How do you pack a powerful punch?

You will need to know the distance between you and the target.

The reason for knowing the distance is for making sure that your fist reaches the maximum velocity before it hits your target. This maximum velocity is usually happens before your fist reaches its maximum reach. Upon its maximum reach, the velocity of your fist instantly drops from maximum to zero. Practice, practice, practice. The traditional martial artist punches a makiwara, a padded board the flexes when correctly punched. It helps teach the proper focus, ranges, and the ability to put the entire body behind the punch, creating maximum power.