My friend Scott gave me a great phrase today. He said that in the church, what we are doing is planting sequoia trees. That is, we are building spiritually mature, Biblically informed, sanctified men, women, and children. But like sequoia trees, they don't start out that way. So you have to plant little saplings, be patient, and have a long-range vision. Meanwhile, do the little things that eventually result in a sequoia: teaching & preaching, care, love, mentoring, and so forth. As the prophet Zechariah put it, don't despise the day of small things (Zechariah 4:10).
The same can be said about parenting. Your goal is a strong, fruitful, healthy adult. But you have to plant a "sapling" and adjust your expectations while he or she grows. You can't get impatient and angry and resentful just because they're not sequoias yet. One day they will be. But for now, you have to do the slow, tedious work of discipline, love, and nourishment.
So, whether you're parenting a child or discipling somebody or leading a church, it helps to remember that you're planting a sequoia. Keep the end in view, but love people for who they are and where they are. It is God "who makes things grow" (1 Corinthians 3:7).