Despite the fact that I went to a public high school, this teacher and I often talked about religion. One of his lessons for me was, "Beware of long-faced Christians." These were the people who'd heard the Good News, embraced it, and got not one ounce of joy from it. You probably know some people like this: folks for whom the Gospel message meant a life of dour belief, sour expressions, and the power to threaten others with eternal damnation.
For years, I've had a little sign hanging in my bedroom, a simple cross-stitched message: "Sursum corda". In Latin: "Lift up your hearts." If you're Catholic, you'll recognize this from the Mass - the priest says it, and the congregation responds: "We lift them up to the Lord." To me, those two words summarize the whole of faith, hope and love: the virtues we need to navigate through this life to the next.
I am not talking about "happiness". I have nothing against "happiness" - I like it as much as the next girl. But happiness is rather fleeting, and typically depends on one's circumstances: I'm happy because I'm comfortable, warm and fed. I'm happy that I got a new pair of shoes. I'm happy because my day went well.
Joy is different. It doesn't depend on circumstances, because it is based on something that never changes: God. Regardless of what happens to me and around me, God (and His love for me) remains. Now, I might have some trouble mustering joy when my circumstances are hard, but that doesn't change these facts: God is. God loves. And God yearns for my eternal joy. And so, I lift up my heart, in joy...today and tomorrow. Even when I don't "feel" joy, I choose to lift up my heart to the Lord. I can smile about that.