Sometimes, what God has in mind is very different from what we want and, at the start, might look like failure or heartbreak. If we allow God's plan to unfold instead of our own, we will find that there is peace in what we saw as failure, joy in what looked like heartbreak, and a deep relationship with the Almighty that develops along the way. It is a kind of "losing our life" that turns out to save it.
This may surprise you, but the word translated as "life" is psychē
We have come to the heart of the matter now, and we may not like it. When we come to Jesus, we often come determined to stay the same. We want to keep our basic "personality" or character. God, on the other hand, is determined to change us, to mold us into the image of Christ. He wants us to become what He intended us to be (holy, righteous) instead of what the world has dictated we should become. He wants to heal our character flaws and make us good, pure. He wants us to be better than we are. God's plan is always for good and not evil, for welfare and not calamity, but we are often determined to have our own way, that sinful, self-centered way that has created havoc in our lives.
Jesus was saying that, when we are so determined to stay the same, in character, temperament, lifestyle, it is not going to turn out well for us. In the end, we will not have the life we expected. We cannot have God's best and our own foolish desires at the same time. It is not possible, because God will not allow it. It's that simple.
We have a choice to make. What are we determined to have? What we want or what God wants? We can't have it both ways. As Joshua told the children of Israel, "Choose you this day whom you will serve." Make a choice. Take a stand. This choosing has eternal consequences, though, so be sure you make a wise choice. Be very sure.