“I have learned to be satisfied with the things I have and with everything that happens. I know how to live when I am poor, and I know how to live when I have plenty. I have learned the secret of being happy at any time in everything that happens, when I have enough to eat and when I go hungry, when I have more than I need and when I do not have enough. I can do all things through Christ, because he gives me strength.” [Philippians 4:11-13]
When your happiness depends on Jesus you can be happy all the time, because you have Jesus all the time.