Then Jesus said to his disciples, "If any of you wants to be my follower, you must give up your own way, take up your cross, and follow me. If you try to hang onto your life, you will lose it. But if you give up your life for my sake, you will save it." Matthew 16:24-25
I'm not sure where people got the idea that God wants us always to be happy. I would argue that if this we true, he would eliminate all the troubles and problems in the world. Instead, Jesus clearly says that we cannot hang onto our lives or anything else in this world. We need to live for the world to come.
Paul was one of the most successful apostles, reaching many people for Christ. He devoted his whole life to evangelizing the Gentiles. Of all people, you would think that he deserves to be happy if happiness is our goal as believers. However, Paul tells us, "Five different times the Jewish leaders gave me thirty-nine lashes. Three times I was beaten with rods. Once I was stoned. Three times I was shipwrecked. Once I spent a whole night and day adrift at sea." 2 Corinthians 11:24-25
And the above was just a partial list of the things that Paul endured. He also lived with "a thorn in his flesh." And he accepted his hardships instead of asking God to take them away. He considered suffering for Christ to be an honor. Unfortunately, that kind of sacrifice for the kingdom is rare these days, at least in the United States. We want God to make life easy and to be happy.
I've had my own "thorn in the flesh" for many years. I was diagnosed with depression in my twenties. For years, I asked God to take the depression away, but he didn't. One night when the depression had returned with a vengeance, I told God that enough was enough. I was tired of climbing out of the depression again and again only to find myself at the bottom again a few years later.
In my frustration, I told God I wasn't climbing out anymore. I was staying in the pit and if he wanted to talk to me he would have to climb down with me. And much to my surprise, he did. He sat with me for a long time and we talked. I again asked for healing. He said he would not heal me of the depression but would heal me of the fear the depression brought.
Before God joined me in the pit, I was sure I would need to get inpatient care at a facility. But after my time with God, depression was no longer my dominant emotion. I found that in my depression I had discovered joy. The depression was there, I continued to take my medications, but I no longer feared future periods of depression.
Joy is different from happiness. Happiness is a result of all the good things in your life; joy is about your intimacy with God. Happiness can be found in hobbies and acquiring things. However, joy comes from God. Happiness is not what we should be seeking from God. Paul tells us what should be important to us. "Always be full of joy in the Lord. I say it again, rejoice!" Phil. 4:4
While God requires us to deny ourselves, he doesn't do it because he doesn't like us, he asks us to take up our cross so that we can know pure joy, as Paul did, which is many times better than happiness because it stays in our hearts no matter what life throws at us. And when we express our joy even in tough times, it may be just the key to open up opportunities to share the gospel.