What does the bible say about being joyful and merry?

Answer 1

So I commend the enjoyment of life, because nothing is better for a man under the sun than to eat and drink and be glad. Then joy will accompany him in his work all the days of the life God has given him under the sun. Ecclesiastes 8:15

God is more balanced than man.

I denied myself nothing my eyes desired; I refused my heart no pleasure. My heart took delight in all my work, and this was the reward for all my labor. Yet when I surveyed all that my hands had done and what I had toiled to achieve, everything was meaningless, a chasing after the wind; nothing was gained under the sun. Ecclesiastes 2:11