I have two suggestions for you. Notice that when I say this kind of things is not me advocating a cure to clinical depression, but I believe it can bring you some moments of Joy.
The first is a bit more superficial. Be a happy-go-lucky person. Even if you will be faking. But the idea is that you will start believing soon that you are happy. And although many people hate this kind of person, it is rewarding when someone compliment you for it. For example, I am having some struggles that make me sad, but whenever I meet other people I turn into this cheerful guy, not taking nothing seriously. Last week, a guy that just met me said “you are always with that smile, that’s nice.” That alone made my day and continue to have this smile even when inside says otherwise. I recommend this movie, where I learnt this concept of Happy-Go-Lucky. It is ok if you don’t consider this advice. Like in that movie actually some people kind of hate such optimistic people. But I have fun with them as well.
The second advice, which is in the context of the Spirituality is that you should be able to find Joy in Christ. Joy in Christ not necessarily means to be the life of the party. In this homily Pope Francis is talking about a Joy that comes from Peace.
How do I find such peace? (Warning: I was accused in another thread of this being Eastern Meditation and not Christian, despite me getting this inspiration in Christian meditation practices but it is up to you). For me it is a matter of using your heart when praying. We often are thinking, using our reason, inspecting the scripture, elaborating our prayers. For me to find peace is to let go of all this over thinking for a moment. For example, imagine, how was Blessed Mary feeling when the Archangel brought the news about Jesus. What were the women feeling when the angel told that Jesus has resurrected. This are just examples, put yourself in the scene, hear the sounds. The Joy will come because you will see that most of this stories are Good News and those bring Peace.
This is long already and I am on a rush. So I just recommend that if you want to learn more, I advice, Lectio Divina and Ignatius Spirituality. Joy comes from Peace.