Sorry you felt that way. I know that feeling. Perhaps it was best if you left, indeed, but maybe if you had a friend along you that could give you confidence, you could've surpassed all of that with ease.
There were some friends in other units I knew from school, but even they ended up discharged one way (mental deterioration of some kind, has to try again some other time) or another (asthma flaring up). My squad also had another 'underdog' I could almost relate to, but even he managed much better than me.
Oh yeah, I don't remember anything from the the last day to morning the day after. Totally blank space in my memory. I've only got memory of making it through the finish line because we had to pass through a river with water at chest height before our 2 km sprint through mud, more water and sewer pipes.
I was pretty small too when we started, but had gained 10 kg at the end and really strengthened my mental fortitude. Obviously your set-backs are something you wouldn't have been able to do anything about. But it would still have been a fun experience had you stuck it out, I think.
It always sucks in the moment, but it makes stories you'll be talking about 10 years from now
There was a free-pace march we had from firing range back to the barracks. That was good shit; wasn't anywhere near the first people to finish, but I was well ahead of the tail-end as well - all without feeling like an exhausted crapsack afterwards.
Unfortunately, I feel like I had such 'core flaws' that trying to "refine" me into a proper soldier would've taken much,
much longer and with a lot more resources than everyone else. Each soldier is a pretty big investment after all, so half-baked results like me would be a waste of time and money.
Some NCO(s) were already a little reluctant about my performance and told me how a normal dude shouldn't have such nauseous reactions to having their bodily limits exerted. This was even more apparent when literally everybody else seemed to perform just fine except me.
Still, I did have fun as well. There was this funny story my room sergeant recounted from his time in NCO training, where a CO got so angry at some dude's rifle he grabbed the gun and yeeted it right up in the air. One of the NCO's had to frantically catch it so the thing wouldn't get fall down to the ground.
And one of our CO's was a little weird. He had this strange mindset about whether Finland would ever go to war. Said smth along the lines of "Well I have all this training (he'd gone through Jaeger training at some poing IIRC), so of course I would get excited if I could put them to use." Kinda MonkaS if you ask me.