Start doing leg presses and squats and learn the facts about where punching power comes from then work on getting more bend in your legs explode from the ground up

Well give it all you got. Try punching your punching bag extremely hard and do it without it a couple of times as well.

Lots of work on the heavy bag

do your knuckle push ups and dips. Also a little bit of shrugs for those shoulders, that should do the trick

I am a welterweight I have been told that I punch pretty hard for my weight..but I want to punch harder

I just cant accept the fact that someone less skilled than me can punch harder just because he weights more..I know that I will never be able to punch as hard as heavyweight but I want to punch as hard as possible as for my weight class..what can I do to increase my punching power?