On a stint volunteering some years ago, Claire Byrne heard from many of her fellow volunteers that they got more out of their volunteering than they put into it. This is an often-overlooked element of kindness, but it's a key part of what makes people help others, when there's nothing obvious in it for themselves.

But what exactly is kindness? GP and mental health specialist Dr Harry Barry gave a definition:

"Kindness is actually a kind of positive behaviour which is marked by acts of generosity or consideration for others. And I think a key thing is that you don’t expect anything in return. That to me that kindness really comes from the heart."

Harry compares kindness to gratitude, in that it’s like adapting a whole lifestyle approach. And studies have shown that kindness brings benefits – not just for the person you’re helping – but also for yourself.

"And I think that’s really important. And I think that’s something that actually, up to this, up to very recently, we didn’t actually see kindness like this, do you know what I mean? We saw gratitude like this, but we never saw kindness like this. And I think a lot of work is coming in to actually back up how important kindness is for us."

Dr Ann-Marie Creaven from the Department of Psychology, University of Limerick, gave Claire her own take on kindness:

"I suppose, like Harry says, it’s not expecting something back. And you could describe it as a genuine, deep concern for others. And while we often think of kind behaviour, so doing something nice for someone else, it also involves an emotional and a thinking piece. So, a kind emotion, for example, might be sympathy for other people. And kindness can be directed towards ourselves."

In terms of benefits acts of kindness can boost a person’s self-esteem, they can allow us view ourselves in a positive light and it brings us closer to people in our lives. And Harry had a few examples of common acts of kindness:

"To me actually, one of the simplest and most profound ones is when you come across somebody who needs that couple of minutes... I actually think it’s really important is that looking out for that moment with that person who everybody else is passing by. How often do you see people just passing people by? And it’s stopping for that second."

Taking time with someone who’s alone or bereaved or struggling with mental health difficulties or childcare arrangements can seem like a small thing to do, but Harry says it’s important and it can have lasting benefits for both people involved.

These benefits are becoming clearer as more studies are done, but when it comes to volunteering specifically, Ann-Marie cautions that the science hasn’t come to a firm conclusion yet:

"The studies aren’t very good at disentangling whether it’s volunteering that leads to better mental health or people who have good mental health are better placed to volunteer."

Can a person be too kind? Yes, according to Ann-Marie and burnout is a real danger, as is self-criticism. The solution is to turn the kindness inwards, as Harry tells Claire:

"The single commonest thing I find is how hard we are on ourselves. We are so self-critical. We are so unkind to ourselves. So, the first thing that I would have to do with people is to get them to adapt a new philosophy and that is that we take on our internal critic."

We all have, Harry says, this internal voice that tells us we’re stupid, we’re boring, we’re horrible. The way to overcome this internal critic is for people to see themselves as normal people who aren’t perfect and sometimes mess up:

"And learn to love and accept ourselves and be kind to ourselves. And funnily enough, when you start being kind to yourself, it becomes a lot, lot easier to then see it, see that kindness being expressed to other people."

My grandmother used to tell me that I’d get my reward for my good deeds in heaven, but – and this something of a relief – Harry doesn’t think we have to wait as long as that – being kind can give us real physiological benefits right now:

"It drops our blood pressure and cortisol. It makes us live longer and healthier. It reduces our cognitive impairment. It ups our positive dopamine and serotonin and out endorphins, so it makes us feel better. It makes us feel less lonely. It makes us feel better about ourselves. It lifts our mood. And very interesting, I thought this was very interesting in the research – there's a huge amount of research that it’s contagious. So, if I’m kind, other people around me see my kindness and they’re kind."

Seems like the sort of thing we should all make a habit of catching and passing on.

You can hear Claire’s full conversation with Ann-Marie and Harry – including Harry’s story of being on the receiving end of an act of kindness from Charlie Bird – by listening above.