"If you know you're a sinner saved by sheer grace, you can take [money or power] or leave it. You're free. If money or power comes, there's a lot you can do with it. But if it's start to go, you know that's one of the ways God's kingdom power is going to work in you life... You work but your work does not define you. You work but it's not driving you into the ground. And you're going to be so content, you'll almost be reckless. People will say "How can you spend your money like that? How can you let that career opportunity go by? How can you be involved with such a needy person when you know she will probably take advantage of you?" A Christian can respond, "It's not the end of the world if somebody takes advantage of me, or if my money is gone, or if my career doesn't develop as I might like. I'm not controlled by that fear anymore." You are replacing the kingdom of this world with the kingdom of God."
Tim Keller, King's Cross