Is this bad?

I have a mild want to punch someone.

Not because I'm mad or anything.

I just want to know if I gave it my all and punched someone in the jaw would they actually be hurt.

I would like to think they would but I've never actually done it so how would I know?

If it comes down to it is this something I could actually use as self defense or do I need to work on other methods?

Anyway, just thinking...