Calming the mind is a central tenet of almost all forms of meditation. Paul says really overstimulating the mind can get you to the same place— maybe because learning to focus in the midst of overstimulation requires the most intense focusing of all? I'm not sure but one thing I do know is that calming those fears almost always involves getting those monkeys to have a little faith.
Faith frequently comes from experience. If you learn how to float and go with the current while getting to the shore you'll be far less likely to fear falling into the stream. Likewise, if you can at least address the fear and anxiety with positive choices about how you might handle those what ifs you can bravely go forward despite the fears. You know you can handle the consequences. When I lived in Santa Cruz, CA and rehearsed fears about what I might do in an earthquake while in my bed at night, my husband helped me calm those fears by intellectually describing where the most structurally sound places in the house might be. My gameplan was to find the nearest doorway (my bedroom doorway is what I always visualized from my anxiety-ridden bed) and stay underneath it. So when the Loma Prieta earthquake did hit in 1989 I ran to my bedroom doorway and did stay safe while chimneys collapsed into piles of bricks, cabinets opened and flung out their contents, and big heavy mirrors and framed pictures fell off the walls and shattered into big shards of pointed glass in the other rooms. Of course, I wasn't actually in my bedroom at the time of the earthquake and there were doorways much closer to where I had been at the time... but it worked out nonetheless.
Giving my mind something to hold onto is a strategy I've used since then with some success. The what if's prefer to have intellectual answers even if the answer is what if that scary thing does happen? Could you live with that? Could you recover? Is the possibility of success worth the risk? If my thought is some version of "I guess so" then I go for it. If not, then I choose another path.
Monkeyflower flower essences all address exaggerated fears. The original Monkeyflower Bach flower remedy, Mimulus, is for known fears rather than nonspecific. People who benefit from Mimulus know what they're anxious about and generally it's the everyday kind of thing like how to make a living, talking with people, being alone, fear of accidents or illness. The remedy brings clarity to those imagined and real fears, quieting the Monkey Mind and enabling the person to develop more courage and confidence.
There are many other essences that address different aspects of anxiety. I have an excellent one for releasing worry and fear that includes Larch (for countering negative expectations), Rock Rose (for deep panic or terror), and White Chestnut (for quieting the mind). There are also other Monkeyflower remedies. I use Purple Monkeyflower (for fears around spiritual or psychic phenomena) in my Trusting Inner Guidance formula and Pink Monkeyflower (for social anxiety) in my Attracting a Partner formula.