Yes, it is IMPOSSIBLE to never be sad even when you are at peace and happy. sadness softens us. anger, instead, makes us harder and we break mentally easier from committing sins when angry. When never commits sins when simply sad.  please cry for your family everyone. cry for your children when they suffer. Cry for your pets when they are gone. Cry to music that brings it in you. but dont get swallowed up in the sadness. find its wisdom. Most of the time that means THINK OF OTHERS FIRST. you will be way wiser that way and kinder and happier. we often cry when we pity ourselves. Crying because we care for others who suffer more than us is very important. It takes the focus on oursleves to God's other creatures. The minimum it does, is bring a sense of connection. and that is pretty deep way to paradoxically, after a good cry for us all, feel better and at peace.