Feeling of not being able to cause damage.

I have never been in a full contact/fight/heavy sparring session in my adult life, and I have this constant feeling that if I hit someone it wouldn't actually do anything to them.

It's the same feeling when dreaming and you just can't hit someone/thing hard enough to do damage or cause them to stop.

I hit heavy bags and mitts + pads, but there's a part of my brain that makes me feel that the kicks & strikes wouldn't do enough damage to defend myself.

My guess is that the answer to this is in the first sentence "Get in the ring and do some heavy or full contact sparring". I am also a very nice guy, so I don't want to hurt anyone, but I want to know if I would be effective in a fight.

I was wondering if this is a common thing that has to be addressed at some point to gain that confidence.

Thanks for any insight.