This elevates your lip so the practitioner isn't smashing your lip against your teeth while treating that area, and it makes it easier to see the fine hairs. It's kind of like pressing your finger against your upper lip when you're about to sneeze. Try slowing down your breathing with deep breaths. Try breathing in through your nose and out through your mouth. Holding your breath and counting to a set number can be good, as can breathing out just after the treatment.
Some people like to hold their breath until a certain amount of treatment has been done.
Experiment and see if it helps you. Try to focus on the feet and legs since they're about as far away from the head as possible. Imagine slowly sinking down into a bath, the warm water gently relaxing each part of your body until you're floating. Another method is to push the pain and stress away from your face each time you exhale. Push the pain down your arms and out your fingertips.