Punching blocks should hurt the player

When a player punches blocks they should hurt the player. Because punching a tree is the first thing you do in the game, it wouldn't make much sense to make it do ridiculous amounts of damage. Maybe it only takes away one health point per block destroyed?

This would add more realism to the game and is an alternative to adding "small stones on the ground that you have to gather to first before (or instead of) punching trees." Starting a survival world by punching trees is one of the most iconic parts of Minecraft, so instead of adding small stones that you have to gather, just make punching hard blocks do a small amount of damage to the player. 

This shouldn't apply to punching blocks like flowers or leaves, and this should only hurt the player, if the player isn't holding an item. If it would hurt you to punch in real life, it should hurt you in the game. Sharp blocks should also be considered, like cacti and glass.