Have you ever noticed that when you are fully joyful, your whole attention is given to that. When you are in awe at the beauty of something, your whole attention is in that. At these times your mind is not preoccupied with worry or problems or doubt. Which do you think is more real --- the times when your whole attention is given to joy or beauty, or the times when you are in worry or doubt? Even if you experience the latter the vast majority of the time, this does not make it true. The way to lessen the grip of worry and doubt is to acknowledge, as it happens, that it is not true.