Our tendency, and I know this well, is to say "here God, I'm commiting this to you and I trust you to help me." And in that moment we mean it. But when we turn around we carry part or all of our concern with us. We give it to God, but we still hold onto it as well and it continues to control us.
We have to commit everything to the Lord and let Him keep it. You will never find peace through the Lord if you don't trust Him to provide it.
It will not happen all at once. When you realize you are holding onto a concern, a judgement, unforgiveness, doubt, or whatever it is -- give it to Him again and again. Each time you turn around you will have less with you and when you give it over again, you will have less still. One day you will realize you brough nothing back, that you gave it all to God. Trust Him and the next worry, concern or whatever, will be easier to let go of, giving it fully to Him quicker.
Committing everything to God, trusting Him fully, will change your life. You will discover a peace you never knew was possible before. A peace that is only possible through the Lord our God who loves and protects us.