how I feel after walking up the stairs at school

That's nothing. I once went to a football match, and the stadium had fourteen flights of stairs to climb to reach the away concourse, as well as more steps to reach my seat in one of the top rows there. Bloody exhausting it was.

Went to see a friend once, the elevator was broke, had to climb 16 levels, I almost died that day

I run 3-5 miles everyday and that still happens to me :/

Bruh, I walked up 32 Flights of stairs and down again at a monument, IN FLIP FLOPS. Get on my level