If you are kind, you are showing yourself and God that you are great and the best self that you can possibly be. Being kind and great has nothing to do with yourself and the rewards that come at the end, but it does have to do with treating others the way you want to be treated and when you achieve this, you don't even think about the reward, only that good feeling. Also, do remember that doing something kind once, can make a difference and then others will follow in your footsteps and be kind to others :)