I have found some good messages in the book Mind Platter by Najwa Zebian, a Lebanese-Canadian author and poet. Some excerpts are as follows.
I cannot count the number of times I’ve been told not to be too nice to people because it will hurt me. After giving this much thought, my response is simple. When I’m too nice because I have a hidden purpose, others have the right to hurt me, because people are not made to be used but to be loved and respected. When I’m nice for the sake of actually caring about others, and living by my values, then no matter what others’ responses are, they can’t hurt me. I tell myself that I am being kind to the world, not specific people. Be content with yourself and always smile. If the world smiles back, that’s great. If it doesn’t, then that’s great too, because despite the harshness around you, you are still able to stick to your beliefs, values and character with a genuine smile.
Between all the rain and shadows, the clouds and darkness, the nights and their troubles, there are moments of sunshine that you must learn to cherish. Just like sadness doesn’t last too long, those moments of happiness might not either. Put happiness in your heart when it comes your way as you would put sadness. You are not being selfish by doing that. You deserve to be happy. And moments of happiness come just like moments of sadness. Moments of sunshine come just like moments of rain. You can choose to bask in the sun, just as you choose to get drenched in the rain.