"I have been crucified with Christ; it is no longer I who live, but Christ who lives in me..." (Galatians 2:20)
According to theologian Oswald Chambers, the verse above means:
"the breaking and collapse of my independence brought about by own hands, and the surrendering of my life to the supremacy of the Lord Jesus [...] It means breaking the hard outer layer of my individual independence from God, and the liberating of myself and my nature into oneness with Him; not following my own ideas, but choosing absolute loyalty to Jesus" (My Utmost for His Highest).
"So I say, let the Holy Spirit guide your lives. Then you won't be doing what your sinful nature craves. The sinful nature wants to do evil, which is just the opposite of what the Spirit wants. And the Spirit gives us desires that are opposite of what the sinful nature desires. These two forces are constantly fighting each other, so you are not free to carry out your good intentions. BUT when you are directed by the Spirit, you are not under obligation to the law of Moses" (Galatians 5:16-18). Earlier in the Bible Paul explains that if we have accepted Christ as our savior, then we are not controlled by our sinful nature, but we are controlled by the Spirit of God living in us (Romans 8:9).
So it all comes down to the idea of letting go of myself and my own independence to choose that which is antithetical to the world's cries for free-choice, for doing what makes us happy. This liberation means that I must exercise my independence by deliberately turning away from my own self-reliance (no matter how much I love Emerson's essay, "Self-Reliance") and relying instead on the help of the Holy Spirit to submit entirely to God.
Why would I want to submit to the will of God? This is a tough concept to explain to my friends who aren't believers. For me, it comes down to two reasons: First, the Bible, which I believe to be the word of God that is backed up by historical accounts (what solidifies the Bible as real and true for me is the book of Isaiah paralleled with the gospel accounts despite the huge time lapse between these two), urges this submission. Secondly, I strive to submit to the will of God because I'm just not convinced that my ways are supreme. When I look at my life and the decisions I've made truly on my own, I see how they've not worked out--how they ended in pain, while the decisions I've made (even if I questioned them) after spending time in prayer and fellowship with God, these decisions have resulted in more joy and more fulfillment. I realize this sounds a bet self-serving, and that's not what I intend. Instead, it's just meant to illustrate that the choices I've made on my own have not worked out well for me. It's not easy to shed our independence and submit totally to God, and I'd even argue that this is a choice we make every day. There may be certain seasons in our lives where we are inclined to rely more on ourselves, so it requires some re-focusing every now and then to get our priorities set straight.