I have to admit this is one of my least favorite popular sayings of Christians. Not because it isn't true, but because of how I perceive it is misused and misunderstood. Many times people will say this in a very passive sense, as if God controlling our lives means we no longer care about our actions or take responsibility for them.
Giving God control of our life does not mean that he does everything for us. It is not an abdication of responsibility. In fact, letting go may mean taking on a greater level of responsibility for work in his kingdom than you ever have before. The only way this wouldn't be true is if you were perfect and had nothing to work on in life. Since none of us fit that definition, God controlling our lives will always mean him calling us to a higher standard.
You may be afraid to let go of control in your life because you know God will ask you to do something you don't want to do. You may even know exactly what it is! Whether it's making a commitment, restoring a relationship, or taking a risk, letting go will mean that God asks you to do more for him, not less. The only question is one of courage and faith. Do I trust God enough to let him control my life and lead me where he wants to; regardless of what it may require of me?
Don't live a passive life. Let go and let God direct your life in the direction that leads to healing and happiness in life.