It's ok to feel sad; there is a lot to feel sad about in the world. It's also ok to feel joy; there is a lot to feel joyful about in the world.
However, feeling sad can be painful, so there might be the tendency to not want to go there. And that's ok as a coping strategy...some of the time. But when we repeatedly deny ourselves the need to feel this emotion, we can start to feel numb. And not just numb to sadness, but also to the joy in life.
There are two sides to a piece of paper, and you can't have the front without the back.
To live and experience life fully is to embrace the full range of our humanness, front and back.