The big idea: does true kindness have to be selfless?

It makes me feel better about myself. It makes me feel better. You would be more likely to do it as often as you could if you were reacting to an activity. We aren't a lot of people looking for ways to find more meaning in life. What is the act that makes people happy? Being kind is the answer.

A growing body of evidence shows that performing kind acts increases mental wellbeing, improves physical health and may even improve life expectancy. It is beneficial for the recipient to be kind.

I was part of a team that created the Kindness Test. More than 60,000 people participated in the online study. The more acts of kindness people tell us, the better they are.

The pleasure of giving can be stronger than the pleasure of receiving a present at Christmas. Sometimes such feelings don't sit well with us. True kindness shouldn't be selfish. It is tied up with notions of self sacrifice and puts other people's welfare ahead of your own. The person performing the act must give up something in order to help someone else, according to some of the research. It is possible that this is the case. If I give up my seat to an older person on a crowded tube, she will sit and I will stand. I have lost out because of my generosity. If you give up several hours a week to volunteer at your local food bank, you are sacrificing time in order to help other people. You don't benefit from your kindness.

When I surrender my seat, or you volunteer your time, we tend to feel a warm glow of self-satisfaction, a glow that shows up in brain scans, a glow that is distinct from the pleasure that we get for ourselves. Reciprocity can help us. At some point in the future someone will act in a kind way towards us when we need help and we can act kindly now, even if it is at some cost to us. Humans have been working together, surviving and thriving for thousands of years.

Why not just celebrate the fact that the giver of kindness, as well as the recipient, has something to gain?

Our brain rewards us for being kind because it pushes us towards that behavior. The biological push doesn't mean the joy is bad. It is similar to sex. Sex doesn't have to be boring when you don't want to have babies.

The advantages we gain from our kindness should not be suppressed. The recipient has something to gain from the kindness of the person. One person giving another person taking is kindness. It is a two way endeavor. When people risk or sacrifice their lives to save the lives of others, it's only in extreme situations that kindness involves the complete or near complete abnegation of oneself. If the hero is still alive, they can personally gain from their actions through a huge enhancement to their reputation.

Less elevated acts of kindness tend to have mixed motives, such as feeling good about ourselves and looking good in the eyes of others. There is a part of being kind to others that is self-interested.

This isn't to say that selfishness should replace selfishness. If the only reason you want to help cook Christmas lunch for homeless people is so that you can post on social media and get a lot of likes from your friends and followers, you should check your motivation. Kind acts shouldn't be done in a cynical way in order to appear more attractive. They have to be believable. If the result of enjoying your kindness is that you do it more often, then that is a good thing.

It can be hard to act kindly. It is true that you shouldn't feel guilty if you experience a warm glow or feel bad if you don't. Donations to charity make us feel good, but the money we give at Christmas actually helps the recipients.

People were asked to describe how they felt after receiving an act of kindness. They said they were happy, loved, relieved, supported or warm. We shouldn't get too hung up on the purity of our motivation if this is the positive impact that we can have by being kind There is a mixture of intentions when it comes to kindness. Lean into those benefits and be more compassionate.

It is possible to find a special gift for a loved one, or to check on a neighbour who is alone. It's a good bet that it will make the festive season more enjoyable for you as well. Everyone is going to win.

The author of The Keys to Kindness is a visiting professor of public understanding of psychology at the University of Sussex.

The Social Instinct is a novel by Nichola Raihani.