That which was from the beginning, which we have heard, which we have seen with our eyes, which we looked upon and have touched with our hands, concerning the word of life— 2 the life was made manifest, and we have seen it, and testify to it and proclaim to you the eternal life, which was with the Father and was made manifest to us— 3 that which we have seen and heard we proclaim also to you, so that you too may have fellowship with us; and indeed our fellowship is with the Father and with his Son Jesus Christ. 4 And we are writing these things so that our joy may be complete.
— 1 John 1:1-4

The Apostle John tells us to find our joy by looking to Jesus Christ. This is an odd thing to say in our culture. We have a tendency to think that joy comes from looking to those things that please us. It comes from pursuing those things that we enjoy. Certainly Jesus is not one of those things. How could he be when he tells us to die to ourselves, to take up our cross and follow him? This doesn’t sound like something we would enjoy! John is telling us that we have it all wrong. Joy comes by looking away from self and looking to Christ.
In verses 1-3, he is clearly talking about Jesus. He is talking about the incarnation of Christ. Jesus took to himself a human nature in order to merit our salvation. That he had a human nature is communicated by John with the words “which we have seen with our eyes, and have touched with our hands.” The Son of God became incarnate. John is directing our attention to him.
He says that he and the other Apostles proclaim Christ to us. They proclaimed the fact that Jesus lived a perfect moral life, that he died a sacrificial death, that he is risen from the dead and ascended into heaven. They proclaimed this to people through the spoken word and the written word.
Why did they do this? He tells us in verse 4 “And we are writing these things so that our joy may be complete.” Do you see what he is saying? Joy comes from knowing Jesus Christ. Joy comes from reading about and understanding who Jesus is and what he did. It comes from the doctrinal content of the Bible. Joy comes from turning away from ourselves and all those things that we think will make us happy and turning to Jesus, the only one that can truly give us joy. 
He gives us joy in two ways. First and foremost, he saves us from eternal punishment in hell. If we truly understood how serious our sins are and exactly what God’s justice entails, then we would be overjoyed to know that God has spared us from this. We ought to remind ourselves regularly of what we deserve and of what God has saved us from. Secondly, a lack of joy comes from being self-centered. God did not create us to focus on ourselves. He did not create us to cater to our every desire. He created us to serve Him. This means that when we cater to ourselves, we have a tendency to lack joy. But when we turn away from self and worship and serve God through Jesus Christ, we find joy. We are now operating the way God designed us to operate.