You are on a journey to the center of God's heart. This trip is a digging process, you start off with your bare hands and this works for a while before you need some simple tools to help you along the way: your Bible is a big help; prayer makes it so much easier to dig too. As you continue you realise that it is backbreaking work but you can do it and you find yourself getting stronger as you go on.
Your hole has now become a tunnel and you are well on your way in this journey, you are going deeper, digging your way to God's heart. After a while you realise that you can't make the tunnel wide enough to fit you and all your stuff through so you start leaving everything behind so that you can make it through your tunnel more easily. You shed worries, cares, clothing, jewelry, people and without these burdens it is much easier to make your way deeper into the tunnel. Eventually you're left with nothing but the clothes on your back. At the next few turns, those too are torn away by the rocks as you crawl through crevices with a new-found strength: you are naked, you have nothing but yourself and you're well on your way to the center of God's heart.
The way becomes narrower still, and as you squeeze through a particularly small hole in some rocks you scrape away some of your skin. It hurts like crazy! You stop for a minute to catch your breath before tackling another small hole. This one takes off a whole chunk of flesh! You cry out, but you realise that without that piece of yourself you can easily get through the next set of rocks. You continue on, finding more and more of yourself being torn away and left along the wayside.
At last you arrive at the center of God's heart, with nothing but your heart and soul left of you. You look back at your broken self and the things you carried, realising that the journey was not very long, but to make it you had to work hard, and give up everything.
Romans 12:1 Therefore, I urge you, brothers and sisters, in view of God’s mercy, to offer your bodies as a living sacrifice, holy and pleasing to God—this is your true and proper worship.