You may think of Thanksgiving as an unhealthy holiday, and if you go back for thirds, you may be right. But a growing body of research shows that thankfulness—the reason for this season—is good for us. Gratitude is good for our mental health and empathy, and also benefits our physical health, helps us sleep better, and may contribute to resilience.

Unfortunately, modern life and politics often work to reduce gratitude and thus to steal away these benefits.

Consider, for example, the idea that each generation should live better than their parents. For most of human history, there was no reason to have such an expectation. There were few technologies that mattered, they were simple, and they changed slowly. Far more important were events outside human control, or at least an individual’s own control: droughts, epidemics, the warlike ways of neighboring tribes. There was little reason to expect any of these things to get better over time.

Parents might have still hoped for, and worked for, better lives for their children. But an expectation, a sense of entitlement for that to happen, would have made little sense. When things got better, there was reason to be thankful. If things stayed the same, or got worse, there was no reason to feel cheated.

The difference is simple. If I expect something to happen, why be thankful when it does? If someone owes me money and pays me back, my saying “thank you” will be an act of politeness more than gratitude. And if they don’t pay me back, I have a grievance, a reason to be angry. Entitlement does not produce thanksgiving, but rather it’s opposite: resentment.

Imagine if Franklin Roosevelt had been with the Pilgrims at Plymouth. He might have told them they deserved “freedom from fear” and “freedom from want.” Or if Bernie Sanders was there to point out everyone who earned less than the 17th century equivalent of $15 an hour. If the Pilgrims had come to believe such things, to believe that they were entitled to success, there would have been no first Thanksgiving. In the unlikely event they survived at all, they would have had no reason to be thankful.

Some suggest that democratic government itself leads to an attitude of entitlement and thus toward a politics of resentment. It’s an easy path to political power, to convince people that only some conspiracy prevents them from getting what they already deserve. Like all great lies, there is usually a grain of truth in it. After all, life, as mother says, isn’t fair. The question for us is whether we will inculcate an attitude of grievance or of gratitude.

Hopefully, we’ll do the latter. After all, it’s good for us.