One that I recently realised and continue to learn about Christian joy was on the list, no. 3.
3. True joy is joy in God and his glory.
When I was a teenager, my Christian friend and I used to compare our "experiences" of God when we prayed. Until one day I realised it wasn't an experience of joy I was seeking: it was God himself. In one sense, we don't seek joy at all. We seek Jesus, and in him we find our highest joy, for he is the desire and delight of all believers. We gladly become nothing, that he may be all in all.
Be sure to read the whole thing. It'll do good to your soul.