GLP, who here can actually FIGHT?

I've been in very few fights in my life. Actually I can think of only 3.

First one I was around 14 and some dude provoked me on the street so I asked him if he wanted to fight, which he did. We exchanged a couple of blows and I somehow got some blood on my lip. Then we grappled and ended up in the floor and I ended up on top of the guy threatening him with my fist. I didn't hit him though, I let him go and he came back treacherously and kicked me to the floor before a security guard in the vicinity dispersed us.

Then at 17 years old I was in NYC and 3 black dudes tried to mug me. I exchanged some unsuccessful punches and defended well but when I was leaving they came from behind and tried to strangulate me. I dropped whatever I had on my pockets and saved my life.

Then when I was around 25 some dude spit at me on my job so I grabbed an iron bar and kicked him to the ground as he was making his way out, then when he stood up I grabbed his glasses and broke them in his face. His tall buddies tried to come at me but I swung the iron bar and hurt his hand. They were off duty cops, they threatened me but after all they left and nothing happened.

I also protected some tourists from being violently mugged by gypsies on the subway. I pushed the gypsies out of the subway but there were more inside and they came for me. I adopted a defensive stance and prompted them to come at me, but they chickened out. Then some security guards came and apprehended them. I had a blade at that time too and I thought I would have to use it, but at the end I didn't even get into any fighting.

Nowadays I carry a fox karambit blade which is legal over here, folks better think it twice about messing with me.

Other than that I did some taekwondo when I was a kid and some box sparring with buddies on the gym (learned to take some punches well). I loved boxing but unfortunately I have some breathing problems and get tired and thirsty too quick, so that made me frustrated and I left it. I still miss those sparrings. Also did a bit of muay thai but the school was too exigent and my shape didn't tolerate it.

sounds like you are more cutout for judo/ju-jitsu/aikido.
If stamina is your problem use your opponents against him.