Gratitude, deeply heartfelt, cancels negative feelings.
Anger, fear, and all that flow from them both can be eliminated in great gratitude, washed away as if they were only illusions.
Which they are.
That leaves sadness as the remaining emotion which people experience that is greatly challenging. I question whether sadness is always a problem. I do not think so, because sadness can come from compassion. Compassion is from Love.
Love is divine in origin, in my view. It is the highest aspect of human emotionality.
So then what to do with sadness?
Reframe it with Gratitude. Use it to take inventory of the reason you are here: to use your gifts to help others. Gratitude will reveal those gifts to you. It will also reveal your opportunities.
Great positive feeling will be the result. You will experience the satisfaction of having done some good in the world, and may even hear the thanks of others. After a point, the latter will matter little, as the highest expression of a life well led is self-respect.