David Hamilton's book, The Five Side Effects of Kindness, is a very interesting read. Being kind makes you happier. The science behind this is that, when we are kind it boosts our levels of oxytocin, dopamine and serotonin which are the body's happy chemicals. It even produces endorphins which are the brain's natural versions of morphine and heroin. So you can get a totally legal high by being kind. The book is full of examples of acts of kindness too. ​If you don't have time to read the whole book, you can check out his blog post here.