40%

We all think we know our limits. Whether you’re exercising, studying, or just trying to break a bad habit, there’s always that moment when you feel like tapping out. To get past that point, Jesse Itzler at Big Think explains a perspective-altering rule he learned from a Navy SEAL who came to live with for a month:

He would say that when your mind is telling you you’re done, you’re really only 40 percent done. And he had a motto: If it doesn’t suck, we don’t do it. And that was his way of every day forcing us to get uncomfortable to figure out what our baseline was and what our comfort level was and just turning it upside down. We all have that will. It’s just a matter of how we apply it not just to the once-a-year marathon, but to a variety of things in our daily lives.

You are more capable than you realize, but you have to fight off the mental blocks you’ve established over the years. You can run farther, you can learn more, and you can resist your vices longer. The next time you feel like giving up, remember, you’ve still got 60 percent left.