Antonyms for the phrase "biting one's nails" could include "composure," "calmness," and "serenity." When a person is composed, they are collected and unruffled, not showing any outward signs of nervousness or stress. Calmness refers to the state of being peaceful and tranquil, free from agitation or turmoil. Serenity suggests a deep inner peace and a sense of tranquility that comes from within. Instead of biting one's nails, a person demonstrating these antonyms might display a relaxed demeanor, steady breathing, and clear, focused thinking. It's important to practice healthy coping mechanisms to keep anxious behaviors at bay and ensure a peaceful state of mind.