"When Jesus says "I am the Lord of the Sabbath", Jesus means that he is the Sabbath. He is the source of the deep rest we need...Most of us work and work trying to prove ourselves, to convince God, others and ourselves that we're good people. That work is never over unless we rest in the gospel. At the end of his great act of creation the Lord said, "It is finished", and he could rest. On the cross at the end of his great act of redemption Jesus said, "It is finished", - and we can rest. On the cross Jesus was saying of the work underneath your work - the thing that makes you truly weary, this need to prove yourself because who you are and what you do are never good enough - that is finished. He has lived the life you should have lived, he has died the death you should have died. If you rely on Jesus's finished work, you know that God is satisfied with you. You can be satisfied with life...
You can take all the vacations in the world, but if you don't have the deep rest of the soul, resting in what Jesus did on the cross, you will not truly rest. On the cross Jesus experienced the restlessness of separation from God so that we can have the deep rest of knowing that he loves us and our sins have been forgiven."
Tim Keller, King's Cross