Its very possible to be incredibly SERIOUS about our Christianity and in the process to lose our joy. I've certainly been this way at different times in my life. I am not saying we should be flippant or not take our faith seriously, but I am saying that whatever we are going to do or be, it should be consistent with the command of Scripture:
"Rejoice in the Lord always. And again I say, 'Rejoice' ". Philippians 4:4
The first thing we are going to need to do if we are going to recover joy or keep joy is to learn to BE THANKFUL to GOD the FATHER. This is a command which applies to our lives at ALL times, and if we spend our time complaining or meditating on things we don't like, we are BREAKING that command.
The next thing we need to cultivate is an attitude towards God of TRUST. We need to TRUST God that He is saving us from sin, changing our hearts, and covering us in the blood of Christ. We also need to trust that God still has good things ahead for us, things that accompany salvation. We have a great inheritance to look forward to. Of course, we need to yield to the Spirit of God to really have this confidence, but in the end, we must learn to trust, for God plays the major role in our salvation. We need to depend on Him. If we are depending more on ourselves, we are either going to be in pride (when we think we are doing well) or in condemnation ( when we are aware that we are not hitting the mark we understand we should be hitting). It is best to humbly trust God and yield to His leading. This will help us to have peace and joy.
The third things we need to do I believe is be committed to the renewal of our minds. Part of this process is to let our minds dwell on things that are good. There are plenty of terrible things going on in the world, but you are not going to be joyful if you are always pondering them. We are not supposed to carry the world upon our shoulders!
I spent some time reading parts of a book by Joyce Meyer on the subject "Seven things that Steal Your Joy". My wife had bought this book so one day I took some time to read through it. I haven't finished the book yet. I will say that I believe Joyce Meyer has a genuine ministry from God. Some people on the internet regard her as a wolf, they find fault with her and so on. Now it may be possible to find fault with Joyce Meyer and some of the things she has said and done over the years. She has been talking and teaching a lot so it would be amazing if there were not some errors in there somewhere. I believe there are some errors in doctrine and practice, but this does not mean that her teachings are without merit. Actually, overall I believe her teachings have done a lot of good all around the world. I believe she has been given some wisdom from God and you can glean some valuable principles from what she teaches on this subject of joy. It is especially pertinent because she admits she was not a very joyful person for much of her earlier life, including parts of her life as a minister of the Word.
In any case, Joyce Meyer lists 7 joy stealers as follows:
1. The works of the flesh, by which she seems to mean self-effort in trying to do the work of God. Biblically, of course, the works of the flesh are wider in scope than simply THAT, and they encompass a lot of evil and sinful behaviours, which I am sure WOULD all be stealers of the genuine Joy of the Lord. But basically, her point here is that if you are trying to live the Christian life or do Christian ministry in your own power, you are going to be miserable. This is true.
2. Religious Legalism
This is a mindset in which we are focused on a set of rules which become the paramount consideration in our Christianity. This approach to Christianity will steal joy because joy comes directly from the presence of God, and from a confident communication with God based on GRACE and not self-righteous worlks. When we are in a legalistic mindset we are always trying to work out with our own minds where we and others are going wrong, where we are failing, what rules we should keep, what we should do, and so on. This mindset prevents a person from trusting in God's righteousness, and from believing that God will do things for us that we don't deserve. Of course, this is just the sort of mindset that will rob us of joy. We will never quite be good enough to consider that we have kept the rules well enough. There is always a further application of the rules that can be found that could be used to make us feel bad, if we allow it to be so.
3. Complicating Simple Issues
We need to embrace childlike simplicity and not try to work everything out if we want to have and maintain joy.
4. Excessive Reasoning
If we are always asking God "Why?" or "When?" we are not in the mode of TRUSTING, and we are rather in the mode of "leaning on our own understanding" which God says not to do. That isn't to say that we shouldn't think about things, but its easy to go overboard especially if we have analytical minds. God however isn't going to give us all the answers we want. If He did, there would be no place left for TRUST. God is seeking to establish the kind of relationship in which we DO trust Him and where we need to be dependent on Him.
5. Ungodly Anger
It should go without saying that if we get angry all the time and hold onto that anger longer than absolutely necessary it is going to take the joy out of life.
6. Jealousy and Envy
Comparing yourself to other people if going to take a lot of the joy out of your life.
7. Habitual Discontentment
If we are never satisfied with what we have from God, if in our minds or with our mouths we are complaining because of things we don't like, or things we don't have that we would like, we are going to miss out on joy.
The mindset of discontentment is something people CHOOSE to have. It is directly contrary to the will of God as revealed in the Scriptures. And it makes sense that if we embrace discontentment with our present life, we are not going to please God or be capable of drawing joy from God.
Well a lot more can be said on all these points obviously, hopefully this has been a good starting point for you in considering what is going on in your own life, and if there are some reasons why you may not be walking in joy.
May God bless you. Its His will for you to walk in joy, why not accept that and choose that way?