If you want to enjoy continuous progress in your exercise practice, there’s a high-level skill that you need to master. It’s not as granular as technique. It’s not as gritty as… grit. It’s bigger and more universal. It’s also easier—by definition. It’s about leaving something in the tank. That means both energy and motivation. The discipline here is to walk out a winner…. To finish the workout with a bit of energy to spare… To end your day with a little bit of juice left over. This approach isn’t always inuititive, especially for the Type As of the world. Yet it works beautifully.

We often blame a lack of motivation for failure. The thing is that humans are pretty motivated. Our restless nature has taken us through millions of years of natural selection. There’s a Lindy effect here that you can’t ignore. People work hard at all kinds of stuff. If anything, we tend to be too indiscriminate in our use of effort. That’s the real problem we’re addressing here.

We all have some level of motivation—big or small. The problem is when inaccurately assess it. When this happens, we fail to match our actions with our existing motivation levels. You can’t drive across the country on half a tank of gas (or a half a charge). Everybody know this—and would never blame their car for this kind of user error. Yet we do this all the time with motivation. The fix: spend less than you have.

We share a cultural narrative of grit and hard work taking you to where you want to go. There are plenty of opportunities for this. There are times to go the extra mile. Absolutely. You can’t do that when the tank is chronically empty, though. It’s also important to note that the kind of performance we exhibit when driving on fumes is far from our best. It’s still fatiguing, though, making it the worst of all worlds. It’s best to stay out of that zone.

My advice: end ~90% of your workouts with something left—the knowledge that you could have done more. You will still improve. You will still adapt. However, you will also enjoy a feeling of success and momentum. These are essential nutrients for progress. Drain them too often and the whole system will get real shaky. So, make a surplus your default strategy. And then, every once in a while—when you’re feeling truly sassy—show the world what you’re made of.