" If you want to be happy, you have to be happy on purpose. When you wake up in the morning, you can’t just wait to see what kind of day you’ll have. You have to decide what kind of day you’ll have. The Scripture says in Psalm 30:5 that joy comes in the morning. When you wake up each morning, God sends you a special delivery of joy. When you get up in faith and make the declaration “This will be a good day,” you answer that knock at the door. You receive the gift of joy God sent to you!
The problem is, some people never answer the door. The knocking has not been answered for months and months, years and years: “Come on! Let me in! You can be happy! You can cheer up! You can enjoy your life!” I don’t know about you, but I’ve made up my mind to answer the door. I’m waking up every morning and saying, “Father, thank You for another beautiful day. I will be happy. I will enjoy this day. I will brighten somebody else’s life. I am choosing to receive Your gift of joy. "

― Joel Osteen , Every Day a Friday: How to Be Happier 7 Days a Week