In another life i took alot of pleasure from beating the shit out of guys who were bigger than me and who picked fights with me. It became kind of a hobby i guess.
A bit of background, i worked in bars for about 17 years and fights, fighting, were readily available. You could try yourself against just about any demo you wanted...military guys fail hard in bar fights btw....not proud to say it but it was a fact....never saw a guy call out his military cred and win. I'm looking at you Fort Drum.
The toughest guys never looked like the image we all have of the toughest guys....EVER. I saw a fucken fat, wrong headed looking guy POUND three musclenuts in front of 100 people....and he didn't lose a sweat.
My point here is don't ever underestimate yourself based on what the other guy looks like.