Kindness is a generosity of spirit. It comes to life when we give of ourselves and our time to be of help to others, without expecting anything in return. When you show kindness to somebody you bring out the best in yourself, and a side-effect of brightening up somebody elses day is to feel happier in the moment yourself.
Pay attention to the impact your behaviour has on others, and notice your own feelings in association to their reactions. And think about how you feel yourself when somebody else shows you kindness. What you give comes back to you in even greater quantity. When you are kind, you not only get an immediate payback in terms of a feel-good factor, you will also receive kindness from others, and in completely unexpected and unrelated ways.
It is so easy to find ways to be kind to others: say something supportive when you instinctively feel someone needs to hear it; offer help without being asked for it; smile encouragingly; swallow your criticisms; listen without judgement; let mistakes slide instead of assigning blame; make small sacrifices for the benefit of somebody in greater need.
A great rule of thumb I apply to my life is to do unto...