There are times when we are sad, and that is normal and natural. Sadness can come as grief and is a mechanism we pass though to help us adapt in tough times. Yet once it passes, when we regain the ability to lift ourselves upward, we can let the little joys of life spark happiness within. Personally, I think that sad and unhappy are two very different things. The first is biological and circumstantial, the latter is when we have the right environment for real contentment and we need to learn to let go of negativity and welcome in positivity. Or in other words, sadness is a thing others can help you to heal from yet unhappiness is a self-improvement project you need to do for yourself.
One can be happy when one stops trying to become happy. When the everyday experiences in living bring you subtle sweet joys, you will find that you are happy at last.