How believing willpower runs out makes it happen faster

HostWe have all been there at the end of a long day where we feel like we just can't handle one more task or say no to one more treat. It feels like we have used up all our self-control for the day and the tank is just bone dry.

HostBut it turns out that how we think about that tank might matter more than what's actually in it. Why does believing we're out of willpower make us hit a wall so much faster?

GuestIt's a really strange loop. For a long time, even the people who study the brain thought willpower was like a battery or a fuel tank. They called it ego depletion. The idea was that every time you use your brain to stay on track, like choosing a salad over a burger or staying calm in a meeting, you burn a little bit of that fuel. By five o'clock, you're running on fumes, and that's why you snap at your family or eat a whole bag of chips. But lately, we have found that this fuel tank might not even exist in the way we thought.

HostWait, so you're saying the feeling of being totally drained isn't actually about being out of energy? That seems hard to believe when I'm sitting on the couch and can't even move to go to the gym.

GuestWell, the feeling is very real, but what causes it's the surprise. A group of researchers did a big test where they looked at how people think about their own willpower. They found two kinds of people. One group thought willpower was a limited thing that runs out and needs to be refilled with rest or food. The other group thought willpower wasn't limited at all. They felt like the more they used it, the more they had, or at least that it didn't just go away like gas in a car.

HostI definitely fall into the first group. I always feel like I have a set amount of push in me for the day.

GuestMost people do! But here is the catch. When these two groups were given hard tasks to do, the people who believed their willpower could run out actually did run out. Their performance dropped off a cliff after the first few tasks. But the people who believed willpower isn't a limited thing just kept going. They didn't show any signs of slowing down. They were just as sharp at the end as they were at the start.

HostHold on, that sounds like you're saying being tired is just a choice. If I just tell myself I'm fine, I can work for twenty hours straight? That doesn't seem right.

GuestNot quite. It's not that you have magic powers. It's more about how your brain decides to spend its energy. Your brain is a very careful budgeter. It's always looking at how much effort something takes and asking if it's worth the cost. If you believe you only have a small bucket of "try-hard" juice for the day, your brain gets very protective of it. As soon as you feel a little bit tired, your brain sounds an alarm. It tells you that you're almost empty and you need to stop right now to save what's left.

HostSo it's like the light on a car dashboard that tells you that you're low on gas, even though there are still two gallons in the tank?

GuestYeah, but for people who believe willpower runs out, that light comes on way too early. Their brain is trying to save energy for a rainy day. But for the people who think willpower is a big, deep well, the brain doesn't send that alarm signal nearly as fast. They keep their focus because their brain doesn't think it's in danger of running out of steam.

HostBut what about the sugar thing? I remember hearing that our brains run on glucose and we need a hit of sugar to keep our self-control up.

GuestThat was the big theory for a long time. They even did tests where they gave people lemonade with real sugar and it seemed to help them focus. But then other researchers tried the same thing with lemonade that had fake sugar. It worked just as well. Just the taste of something sweet was enough to tell the brain, hey, we're getting fed, you can keep working. It was the signal, not the actual fuel, that made the difference.

HostIt feels like we're just playing a trick on ourselves then. If I know it's a trick, will it still work?

GuestThat's the big question. It's hard to just flip a switch and change what you believe. But knowing that the tired feeling is often a suggestion from your brain rather than a hard physical limit can help. When you feel like you can't do one more thing, you can tell yourself that this is just your brain trying to be cheap with its energy.

HostSo if I stop seeing my focus as a battery that drains and start seeing it as a muscle that gets stronger, I might actually have more of it?

GuestIn a way, yes. People who view a tough task as a way to gain energy rather than lose it actually end up doing better the longer they work. They see the effort as a sign that they're getting into the zone, not a sign that they're falling apart.

HostMy afternoon slump might just be a story I'm telling myself to get to the couch a little bit sooner.

GuestResearchers found that when people saw a hard mental task as a way to get fired up instead of a way to get worn down, they didn't show any signs of slowing down at all.

HostThat gas light in my head might be coming on way too early every single day.