There is a girl... or better a woman, who used to be my friend for many many years. It is not the case anymore, as we have grown apart. I can't say I have the same admiration or love for her as I used to and it is probably the case the other way around.
But there is something she did I will never ever forget or be any less thankful for it till the end of my days. For my sixteenth or seventeenth birthday she gave me a notebook filled with wonderful quotes and messages of love and respect for me. It didn't cost money: but in time and patience it was worth millions. Here I was, a fragile (if happy) and insecure teenager, with an entire notebook of love dedicated to me. You can not imagine how wonderful this felt, and in times where I felt my lowest I would think; " It can't be that bad, there it is in the notebook, black on white, saying I am special!"
The point I am trying to make, I guess, is that kindness and love never ever go to waste.
And I am not talking about just your everyday being nice and civil to people, I am talking about active acts of love. I am not saying this will return to you in any way, or that you might be happier for it or that world will be a better place. All this might or might not happen. But you will definitely change someones life, even if that person doesn't know it than.