Francis Schaeffer, in his book True Spirituality, writes of the necessity live in the gospel moment by moment.
“I became a Christian once for all upon the basis of the finished work of Christ through faith; that is justification. The Christian life, sanctification, operates on the same basis, but moment by moment. There is the same base (Christ’s work) and the same instrument (faith); the only difference is that one is once for all and the other is moment by moment.”
This is super-helpful stuff, and reminds me a lot of Luther’s directive constantly to press justification into the heart, or as some say, to preach the gospel to myself every day.