[thenerdhead]

I never experienced a runner's high or a basketball "lock in" until I did it enough.

I had to build the endurance to go over 6 miles without stopping to experience my first runner's high.

I had to last a whole half in a basketball league to experience being in the zone.

It took me a couple years to even get the feeling, but now that I've experienced it, I can't stop doing it. I think there's a personalized threshold for everyone, but for me, it was pushing myself quite far beyond my limits.