Every person has comfort zones within which he or she operates. Physical comfort zones are easy to identify. Somewhere around 100 yards you would stray from your comfort zone. Psychological comfort zones are a little harder to quantify.
Most people find talking to a friend or a few friends at once to be no challenge at all.
However, the thought of standing up in a room of twenty or thirty people to give a 5 minute speech, even if it is on a familiar topic, is enough to cause goose bumps and moist underarms for the majority of people. The key to personal growth and increasing success in nearly every endeavor is the willingness to step outside of one's comfort zone. In swimming this might mean doing something physical like swimming a particular set all fly instead of all free, or choosing to go on faster intervals or leading the lane instead of drafting off the leader. It might mean doing something more cerebral like deciding to enter your first meet or setting a goal to swim a personal best time and then training toward it. Virtually everyone enjoys the feeling they get when leaving their comfort zone results in success.