This is probably a question that can only be answered satisfactorily by knowing more about the specific problem that is causing the lack of peace. But, some things that can be looked at are: (a) is there a good foundation, based on the Word of God, on how God works? (b) Is there any doubt as to how much God loves you? Jesus in the gospel of John spoke of the peace He was going to give the believer. If that peace is not being experienced, then perhaps there is a lack of understanding on how we are to walk out our relationship with Him. It becomes important to identify if what we are experiencing is concern or really worry.