You do treadmill or run at a trail? Do you do that workout where you run in place but your knees go high as you do it quickly in bursts?I feel you, but I saw some guys in boot camp who I thought wasn’t going to make it but surprised when they made it out on top.
I’ll use me as an example
Before boot camp I could barely run half a mile, now I’m able to run two miles at least three days a week.