When I was in college, I studied human services. One of the theories of styles of therapies that I learned about was something called Reality Therapy.
In general, this means that you go through the motions, the steps, until you accomplish what you are setting out to accomplish - Usually, this means mustering up a feeling. Even though you don't feel it - You just go through the motions until you do. This is how it is with joy sometimes.
It's going to sound so simple, and naysayers will say, but you have to feel something in your heart before it truly means anything. But, that's really not always the case. Sometimes, it's in the action of doing that the feeling is born.
Just start with a smile. Keep smiling until you feel the joy!
While joy is far deeper than happiness, the act of smiling does so much for lifting our spirits and emotions. When we smile at someone, they tend to smile back. When we smile, we look happy, even if we don't feel it.
I'm not talking about putting on a mask to fool everyone around us while we are aching inside. I'm talking about going through the motions of gladness even when we don't feel happy. Not with the intent of masking pain, but rather with the intent of generating joy.
It start like this - SMILE! Just smile. It may begin as a grimace, but that's a start. They say it takes 3 weeks of doing something before it becomes a habit. So, set out to purposefully smile for 3 weeks. When you notice your face has gone somber, change it to a smile. When you see people, smile at them. When you feel anger or emotions that are about to steal your joy creep in, smile instead. If after 3 weeks of smiling in exchange for other more damaging expressions, you still don't feel even a tinge of joy - Then, maybe the reality therapy isn't what is going to do it for you. But, it's worth a try.
Is joy something you can muster up all by yourself? I really don't think so. I really believe that true joy is only found when we are in the presence of God. The Bible says:
You will make known to me the path of life;