Thinking has a profound effect. So does not thinking.
A mind obsessed with yesterday's events, today's pains, and tomorrow's dark clouds creates problems where none truly exist. It transforms daily dreams into realities, a molehill into a monstrosity, innocent creatures into venomous snakes. This is all the more true when these words pass from our lips into the world we all share.
That's why letting go of these thoughts is such a powerful way to heal—for all kinds of illness. Distract your mind with good thoughts, productive thoughts, thoughts of trust in the God who made you, and especially thoughts of Torah.
Heal your mind and soul. You will heal your body too.