This is an analogy I’m toying with. Please let me know your thoughts, and suggest any corrections, additions and corresponding Bible verses.
“Imagine being in a small, narrow bay, a sound. At one end of this bay is happiness, joy, gladness and the other end is sorrow and sadness.
Our boat is our well-being, our emotions, simply how we are doing. It is our soul, our heart, our life.
Our boat is moved by the wind and waves and tides of life, and our well being moves towards or away from happiness.
Many people’s boats move up and down the bay, changed by the realities of this world but completely unhinged from anything that could give them constancy.
But for the believer, their boat is fixed to bottom by an anchor, linked by a chain, and that fixation is Christ, his goodness and happiness.
Are Christians moved by the ups and downs of the circumstances of life? Of course we are.
We groan and rejoice as life comes towards us, but we aught never to be unhinged. The anchor of our faith is the same yesterday, today and forever.
Now some people’s chain may be longer than others, and they move and sway more due to circumstances. This may be due to a variety of factors, both of nature and nurture.
There remains a very practical question, ‘Can we grow in our happiness?’ Can we grow in the range of pleasure and sorrow that our boat travels?
We cannot change the tides or the wind, but what if what we connect to at the bottom of the bay runs the length of the bay, and we can move our anchor along it? What if it is a long line that runs along, and we can move the anchor of our chain up and down this line on the bay.
I believe we can. Perhaps this is what the God means, when He says through Paul, ‘Therefore, my beloved, as you have always obeyed, so now, not only as in my presence but much more in my absence, work out your own salvation with fear and trembling,  for it is God who works in you, both to will and to work for his good pleasure. (Philippians 2:12-13 ESV)
We aught by the power of the Holy Spirit to do Bible study, prayer, worship, fellowship, evangelism and ministry and thus become more happy. We aught to pursue digging out the parts of our nature and nurture that have caused our anchor to be too far downstream, into doubt and sadness. The gear that moves us upstream can sometimes get stuck, and we need the help of God and the help of others to get it unstuck, that we might move further up the bay, into the delta and into the river, the river of God.
 Then the angel showed me the river of the water of life, bright as crystal, flowing from the throne of God and of the Lamb  through the middle of the street of the city; also, on either side of the river, the tree of life with its twelve kinds of fruit, yielding its fruit each month. The leaves of the tree were for the healing of the nations. (Revelation 22:1-2 ESV)
Eternal happiness, joy, rejoicing and gladness awaits us with God in the new heavens and the new earth and we aught to pursue this same joy in God doggedly here on earth.