Philippians 4:4, Rejoice in the Lord always; again I will say, rejoice!
This verse sounds like a command, because it is. God wants us to be joyful. Living in joy is a choice. It is allowing God to do His work in our hearts. It is the natural outworking of the Holy Spirit in us (Galatians 6:22).
But why do so many Believers have so little joy? Many (dare I say, most) are angry, bitter, worried, and fearful. Maybe some do not know that they are supposed to live in joy. That is a shame. It is a wonderful gift! Others may not think they deserve to live in joy. But it is a free gift from the heart of our loving Father. Still others focus on their hurts, the abuse they have suffered, their lack of something that others are perceived to have, etc. For whatever reason, they exclude themselves from this inner effervescence of Life.
We are given a choice everyday to live in joy, or in some miserable state of mind. I am not a really smart guy, but when given a choice of joy or anger, bitterness, worry, or fear, I think I will choose joy.
A life of joy can be difficult to start. We have deeply entrenched ourselves in horrible thought processes. Sometimes our poor ways of thinking have been handed down from generations past. Depression, fear, or anger can be carefully taught by parents. A life of joy might be hard to start because our family and/or friends need for us to live in misery, so they will not feel alone in their misery. But this pattern is not for us any longer.
It is time we all started some choices that have no downsides. Let’s start our day with joy and not give control of our attitude to anyone but the Holy Spirit!
Shepherd's Heart Ministries 
I don’t believe that a parent “teaches” things like depression, fear and the other things mentioned . Children learn more by seeing the lifestyle of the parents in all that they do. There is a Jewish word for this and I don’t want to chance getting it wrong . What a child sees while growing up is “normal” to him or her. I believe that this is a very deep issue effecting the formative years of one’s life.
Exactly my point. Parents “teach” their belief systems, good or bad. As parents we should be diligent in serving the Lord with joy, for the Kingdom and our children’s sake!