Proverbs 15:15 All the days of the afflicted are evil: but he that is of a merry heart hath a continual feast.
The Bible says that being merry (cheerful) is like having the choicest food every day of our life. Yes, the merry heart is a feasting heart. Mish-teh, the Hebrew word for feast, is a symbol of gastronomic banqueting pleasure.
The Bible says that a cheerful heart has medicinal properties, for it protects the mind and the body from ailments that are a result of stress. Therefore being happy is adding to our overall well-being, Pro 17:22 A merry heart doeth good like a medicine: but a broken spirit drieth the bones
Conversely, being sad can crush, crush us of everything that the French say is: joie de vivre (a feeling of great happiness and enjoyment of life). And sadness by the way is the emotional attitude of the ungrateful person, for he always looks at people better, for he never counts his blessings, and in due course of time, he shrinks: shrines mentally, emotionally and spiritually.
Also, being happy is a commandment, for Jesus said: take no thought for your life. Taking thought, that is worrying, is in violation to Jesus’ commandment. Worrying is sinning. Worrying is questioning the ability of Him who said: if He can take care of the birds in the air how much better could he take care of us.