A kind gesture can reach a wound that only compassion can heal. 
— Steve Maraboli

All positive effects summarized briefly and concisely: acting on compassion and kind and loving friendliness makes you socially strong. This also reduces stress and anxiety and is therefore good for your health.
Finally, it will help you to see yourself as capable and useful which will increase your happiness.

When these conditions are met, one reinforces the other. By your kindness, you become happier and with that more friendly and so on. And the fun is, it is contagious too!

It also makes you more attractive. A study examining the trait most highly valued in potential romantic partners suggests that both women and men rate kindness as one of their most desired traits.

https://medium.com/publishous/the-secret-to-happiness-is-compassion-e50b37b2a190