What do you believe about your capacity?

I’m a big fan of David Goggins. He is a powerhouse. David does things that I imagine no human should be able to do. He is the only person ever to complete Navy Seal, Army Ranger, and Air Force Tactical Air Controller training. He also held the Guinness World Record, doing 4,030 pull-ups in 17 hours. Goggins talks about how when you feel you are finished and physically worn out, your brain is trying to keep you safe. In reality, you still have 80% more you can give.

In The Magic of Thinking Big, David J. Schwartz writes:
Capacity is a state of mind. How much we can do depends on how much we think we can do. When you really believe you can do more, your mind thinks creatively and shows you the way.

Our capacity for physical endurance, work, or any other struggle is likely much higher than we believe. What we believe about our capacity also limits or unlocks our abilities.

So, the question is, what do you believe about your capacity?