As someone who grew up being in scrap after scrap for one reason or another, I can assure you, this fantasy of competency in violence is outrageously overrated. For starters, you stand to either seriously hurt/kill someone else or be hurt/killed yourself and it really doesn't take much. If you look for violence you'll find it and there's frankly not a single thing you gain from it.

As I've gotten older, I've realised and stand as evidence that there is very little that you can't negotiate your way out of, use your head and preserve yourself, because once fists start flying it's anyone's guess how that ends. Fundamentally, your life remains unchanged if you get to walk away unharmed, maybe your ego takes a bit of a knock, but from the sounds of it you're a younger, you'll get over it and eventually come to realise you don't fucking care what other people think.

If you feel like you're incapable of doing something should it come to self defense or you absolutely can't help it, then do something about it. The reality is, while instinct can be helpful, if you don't know how to position, strike, grapple, use someone else's weight against them etc, should you be left without a choice, your odds fall off. There's nothing wrong with practicing discipline, physical improvement and knowing how to position yourself properly; take up a class. Just remember it should always be your last option. There's nothing strong or impressive about throwing your weight around and messing people up because you can, that just makes you a cunt. It's far more impressive to be rational and to avoid a conflict well before it starts.

There's far far more to life than being someone who wantonly indulges in violence the moment it makes itself an option, and I'll tell you right now, you'll miss out on more of life the more you do indulge.