Eugene Peterson relates the following description of the formation of a glacier:
A glacier is the most powerful force the world has ever seen. Nothing, literally nothing, can stop a glacier. A glacier is formed by the falling of snow that accumulates over a period of time—an inch today, a quarter of an inch yesterday, a mere skiff of powder last week. As the snow deepens, the weight compresses. Ice is formed, and then more snow, which becomes more ice, year after year after year. Nothing happens for a long time, but when the glacier is sixty-four feet thick it starts to move, and once it starts nothing can stop it. (from Christ Plays in Ten Thousand Places, p. 338)
Peterson’s glacier illustration challenges me when I think about my own spiritual formation. When I think about the fruit of the Spirit (Gal. 5:22-23), I can’t help but notice how slowly some of that fruit grows. Love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, and self-control need time to form in us as the Holy Spirit keeps leading us to mature in holy living and Christ-likeness.
It will take spiritual disciplines to keep us growing over the long haul. We can easily be drawn off the path, failing to submissively cooperate with the work God is trying to do in our hearts. Holy habits such as spending time with God through Scripture, in meditation, and in prayer (to name just a few) can help us continue to “walk by the Spirit” (Gal. 5:16).
Glacier formation helps me think about some avenues of spiritual formation. Cramming won’t cut it. Shortcuts cut our growth short. We cannot do decades worth of reading or praying or meditating in a day, but we can set in motion today what God will do in us in years to come. We can start today down the path of becoming the disciple of Jesus we will someday become. 
We can walk with God and enjoy the journey of growing at the speed of glaciers: steadily, obediently, and persistently. A prayer here, a skiff of a word from God there, an accumulation of days and weeks and months of worship and fellowship, humble service rendered in daily installments—all of these things may seem quite common; no bells or whistles go off when we take part in them. But in all these common ways, God will work slowly but surely in our hearts. God will work hourly, daily, and powerfully toward his goal of forming Christ in us (Rom. 8:29; Phil. 2:13), with an eye cast to the horizon and vistas of things to come.