From All Is Happiness (#E-60) by Rabbi Avigdor Miller
You have to look for happiness. If you look, Hashem will help you find it.
Who is the one who sang to Hashem in gratitude and in joy more than anybody else? David Hamelech. The whole Tehillim is mostly:
Hodu lashem ki tov, kiru bishmo — Praise Hashem because He is God; Call in His name.”
“Ki simachtani Hashem bifaalecha — You made me happy, Hashem with your work.”
“Bimaasei yadecha aranein — I sing at the deeds of your hand.”
David sang all his life to Hashem, so we see that David was a man who utilized his life despite all the things that happened. Sometimes there was a little break, or maybe a big break in his life, but when it came back to normal again, he utilized everything.
You have to study Hashem’s kindness, otherwise, you're missing out on the purpose of the world
“Kol atzmosai tomarnah Hashem — All my [parts and all my organs and all my] bones say to Hashem — mi kamocha — who is like You?” (Iyov 19:26). Your heart is working well? Thank Hashem! Your lungs are working well? Thank Hashem! Not everybody’s lungs are working well. Your eyes are working well? Thank Hashem; many people are in the eye hospitals today. Your kidneys are working well? Many people are on dialysis; you’re not, baruch Hashem! You have to study these things, otherwise, you're missing out on the purpose of the world.
Hashem said, “Olam chesed yibaneh” (Tehilim 89:3), the world was made for kindliness. If you're not going to study my kindliness and you'll keep on waiting for something else to come along, if you neglect to see what you have now, you are not fulfilling the purpose for which I made you. The purpose is that you should sing to me and study the things that you do have already.