It can be difficult to admit irrational anxieties to oneself- it's admitting weakness, fear, irrationality, and a waste of effort all at once. Considering one's worries, however, can free mental space and effort for more enjoyable things.
To start, find your favorite meditative state, whether that be sitting in a meditative posture, laying on your back, or performing a meditative movement. Make sure your environment doesn't allow for interruptions.
This meditation first involves triggering your imagination. To prime your imagination, simply allow whatever thought that appears first to be a point of focus, whether that is a color, an image, or a whole memory. Exercise your focus on the object of your imagination. Take a few moments and try to hold that object in your imagination steadily while you observe various characteristics- the feeling, the sight, sounds, and other sensory imaginings.
Take a few minutes to relax while considering whatever the object of your imagination is, because the next step involves replacing that object with something frightening.
While imagining, it's important to recognize your control over your imagination. You can make the imagined object appear and disappear, and even change. This control is the foundation for the next step of exploring your fear. Control within the imagination is more easily achieved over time, so be patient with yourself and don't progress until you feel ready.
The imagination allows a buffer for reaching a logical conclusion in the face of your fear, rather than an emotional reaction to it. Discovering this logical conclusion to your fear may actually be pleasureable, like being relieved of a long-held weight or an uncomfortable joke suddenly ending with an innocent punchline. This relief comes from the realization that there is nothing to worry about.
From the distance provided by your imagination, your thoughts will be very informative in indicating the source of your fear. By recognizing the thoughts your imagined fear triggers while you are observing the frightening thing, the irrationalities of your fear will become easier to recognize.
For instance, most spiders cause irrational anxiety, and it's easy to imagine a spider crawling into your peaceful imaginative state. While focusing on the initial object in your imagination, introduce any aspect of a spider you find disturbing and allow the feeling to settle in- feeling one run across your skin, suddenly finding one hanging near you, or if the spider's somewhat torturous methods of eating disturb you. Remember while in a peaceful state you have control over your imagination. With this distance and feeling of control, listen for whatever thoughts surface, and you'll probably find reasons to not fear- "Spiders here aren't poisonous," and "I'm too big of an animal for a spider to eat me" are very useful realizations for arachnaphobics. Extend this exercise into any realm of anxiety, such as social anxieties or a fear of heights, and more useful fears to resolve can be discovered.
In summary, first find a comfortable physical and mental space where you don't anticipate any interruptions. Imagine an object until you feel relaxed enough and ready to introduce the object of your fear. Next, bring your fear to the forefront of your mind- imagine the the feel of it against your skin, the sound of it, the sight, smell- whatever comes easiest. Try to steadily hold this sensation in your imagination and expose yourself to the fear as much as you feel comfortable with. Listen for thoughts that highlight why your fear is irrational, and let those thoughts guide your meditation to associate you differently with the initially fearful topic.
As a further step, you might imagine your fear becoming even worse. For instance, you might you might imagine reaching into a dark hole where you know a spider is hiding, or possibly becoming a spider's mummified victim. Push the boundaries of your fear once you are more comfortable doing so.
This meditation of bringing fears to the forefront of your imagination is useful for discovering which of your fears are irrational, and it's also useful for confronting fear to learn how to resolve it. While some fears are truly worth more worry and consideration- those which are inevitable- many fears are truly not worth the effort.