The phrase "have a fit" means to experience a sudden outburst of anger or frustration. The opposite of having a fit may involve maintaining composure, staying calm, or exhibiting patience. Other antonyms for "have a fit" include remaining tranquil, peaceful, serene, collected, or composed. Instead of expressing angry emotions, one may choose to approach the situation with a level head and a rational mindset. Alternative phrases that could be used in place of "have a fit" include "keep your cool," "maintain your composure," "stay level-headed," or "preserve your serenity." It's important to recognize the value of maintaining emotional stability, especially during stressful or challenging situations.