Joy
There is a difference between joy and everything else. And that distinction matters.
So often, we let our circumstances dictate our happiness. But they cannot dictate our joy, because joy is not flippant. It is constant.
Three examples:
From a daily perspective: Today, I felt sick. But I was joyful. Not happy that I wasn't feeling well, but glad that I've been so healthy in life. This sickness? A blip on the sick-radar. And correspondingly as bothersome.
From a continual perspective: my car recently broke down. But I was joyful. For three months, I was using friends' cars. Hitching rides with friends. Walking more. But a car doesn't provide me with joy, only the ability to get from place to place more rapidly than I'm able to on my own. So, I bore that. And eventually, another car was provided for...but the joy came long before.
From a lifetime perspective: 26 years ago, my father died. I'm still dealing with that today. But I am joyful for having him for as long as I did, and for the lessons I've learned since.
Being joyful is not about fakeness or defense mechanisms. It is about understanding the true status of the world—that all things lay in more important matters...the matters of our hearts, and how (and more importantly why) we take the love from there and use it to care for those around us.
We were made to do such. This is what brings us alive. And this is what keeps us joyful in times of celebration, and in times of trial.