Sadness and happiness are common to all living things.these are like two side of same coin.the end result of any action we take is to experience sadness or happiness. I see these as condition derived from universalty rather than ordinary feeling.
Happiness comes frome being able to do something as we want it to be done.for example ,you passed the exam because you worked hard.sometimes we also get pleasure from the action of other.for example sri lanka team wins the cricket match.happiness is also comes from thing that happen in nature.like being able to feel the cool breeze on a hot day.An aesthetic things also bring happiness.like listening to a song,watching a movie,watching a dance ang watching a drama.The primary purpose of any living being is to find happiness.but happiness is not an eternal ,permanent thing.
Sadness comes from not being able to do anything we want to do.for example you practiced hard but you failed the competition.Grife is caused by the action zone of other.like separation of the closest person.Grief can also be caused by things like disappointment ,illness and separation.It is a very intense ,stressful feeling.No one love misery.As some your activities may cause sadness to other.There for be mindful of what you do.
The feeling of happiness is associated with laughter.Grief is associated with crying,fear,depression and nausea.There for ,life is ikely to suffer for a long time.living as simple as possible can reduce suffering.
I wish everyone a happy life.keep your smile in every time.
