Do you need a reason?

Can't do it?...

Try this:
Look at the problem.
Smile at it.
Say:"Just try an hold me back."
Do it.

It works every time.

No. It's not easy.

Like right now: last set of Arnold press.  On one side the guy's socks smell like rabbit glue. On the other side the guy's sweat is like anti air. I think I might die if I don't run. But I'm gonna finish. All the sets. All the reps.
Just try and hold me back.

Shoulders: killed.
Gains: coming soon ;)