Galatians 5:9, NIV:  "A little yeast works through the whole batch of dough."

Have you ever watched someone knead dough by hand? Have you ever tried it yourself? It may not be the most difficult thing to do, but when doing it, you realize why it’s said that the ingredients have to be ‘worked’ in. The Christian life is much the same. The right ingredients must be ‘worked’ in—kneaded in as such that the things of Christ are blended and permeate your whole person. That’s something that takes time and energy.
We cannot approach our Christian life like pouring syrup over ice cream and expect it sink into us deeply. Short daily quiet times are fine, but not enough alone. The more time we spend working in the good ingredients, the better we’ll be at keeping out the bad ingredients and worldly influence. It is just as it has been said, “Anything worth having is worth working for.”