I've been following the work of Dallas Willard, Richard Foster, and others in the spiritual formation world. ("Spiritual formation"—the pursuit of being formed in the image of Christ, the progressive renewing of our minds/hearts through practices and community, by the Holy Spirit.)
I deeply appreciate their practical insistence that the new life described in the Gospels and New Testament is not theoretical or merely "positional"; it's actual. It is a new kind of life. And then they set about showing us how to find that life.
All this is helpful, but it is very hard to teach without stumbling into legalism. (Not their fault. It's hard to do anything without it becoming legalism.)
What I want to add to their program: all spiritual disciplines and practices are about living inside the Gospel. They allow us to remember the Gospel, daily.
Prayer, Bible study, fasting, service, solitude—none of these make us good. They help a Christian to experience the truth—they are already new in Christ.
I find this kills legalism right off the ground. If my actions aren't about changing me, but accepting God's inevitable decision to change me, then I won't be proud. I'll be thankful, and trusting.