Some wise counsel from Henri J.M. Nouwen in Here and Now:
One simple answer is to move from the mind to the heart by slowly saying a prayer with as much attentiveness as possible. A prayer, prayed from the heart, heals.
As you lie in bed, drive your car, wait for the bus, or walk your dog, you can slowly let the words of one of these prayers go through your mind simply trying to listen with your whole being to what they are saying.
You will be constantly distracted by your worries, but if you keep going back to the words of the prayer, you will gradually discover that your worries will become less obsessive and that you really start to enjoy praying.