The doctrine of the blessed hope is the greatest contributor to holiness. If you believe in the imminent return of Jesus Christ, you will live a holy life. It will absolutely provide all the external motivation that is necessary. All of us need external motivation. We all need to understand that there are benefits and consequences to all our actions. These benefits and consequences direct us and are not purely internal motives.
To live expecting the imminent return of the Lord will keep your life sanctified. If you believe Jesus can come now, you will make the right decisions at every moment. He didn't come then, but He could come now
Living with the expectation of the blessed hope will feed into sanctified living - a godly lifestyle in this ungodly world. Clearly understand that the blessed hope, the expectation of the Lord's momentary coming, will cause a pursuit of sanctified living.