If you are sad and anxious go to a lake and watch the water coming to shore and going back to lake again in flutters.
Water is coming to the shore in the hope that shore will keep it with itself. Shores cant keep the water so it has to go back to where it came. In life also we meet and we depart . None can live for ever only some memories will. Memories associated with gardens flowers lakes last longer. Japanese proverb says Things come in a bundle like happiness and sorrow. If you are having one now the others will follow.
The best way to be happy is to live with nature.
Nature can make you happy Nature can make you forget your sorrows.
If you are happy you will not have diseases which are caused by life style of modern day diseases like hypertension and blood pressure. Doctors will know and tell you better.