We write this on New Year’s Eve, the time of year when we make New Year’s Resolutions. These usually involve health: Drink less. Eat better. Exercise more.

Many of us will embrace the growing tradition of “Dry January,” where we drink zero alcohol during the first month of the year.

Others will jump on the fasting bandwagon, regularly going 24 hours or more without eating any food.

Whatever your resolution, you should consider what happens after your initial surge of motivation. What happens in February — after Dry January?

What happens the day after your fast?

What happens when you go OFF your diet?

The bad news about resolutions is that they’re made in a fit of motivation. But motivation never lasts. Never.

The good news about resolutions is that they actually lower your need for motivation. Let me explain.

We’re all governed by something called hedonic adaption, which is that our enjoyment of things is governed by recent experiences. For example, an average slice of pizza might be heaven for a sailor who’s been on a submarine for six months, but hell for someone who’s spent the last six months in Naples, Italy.

Anytime you engage in something that takes will power — say, fasting for a day — the difficulty of it has to be matched by your motivation. High difficulty requires high motivation. When your fast is over, your motivation might be lower. But so are your expectations for how much or how often to eat. Take advantage of that.

How? The best practice is to resume with half. So after fasting for 24 hours, start fasting every day for 12 hours. Or better yet, 15 hours. In other words, skip breakfast. You’ll have less motivation. But you’ll need less. The benefits of fasting for 12 of 15 hours every day are huge.

After Dry January is over, resume drinking only half the amount that you used to.

After training for (and running) a marathon, resume training at half the intensity.

Doing something that requires huge motivation gives you a gift, which is that it resets your hedonic adaption and enables you do to more than you used to with less motivation.

So after your New Year’s resolution is over and done, don’t go back to the old habit. Maintain half of whatever you did during your surge of motivation.