John Glenn knows a thing or two about fear. He was the first American to orbit the planet and was venturing into a world that was fraught with unknowns and danger. Heck, the trip started by being launched atop a intercontinental ballistic missile.
In his pilot's flight report for this mission he outright addresses this fear:
Many people were concerned about my mental state during this and earlier delays, which are a part of preparation for a manned space flight. People have repeatedly asked whether I was afraid before the mission. Humans always have fear of an unknown situation — this is normal. The important thing is what we do about it. If fear is permitted to become a paralyzing thing that interferes with proper action, then it is harmful. The best antidote to fear is to know all we can about a situation. It is lack of knowledge which often misleads people when they try to imagine the feelings of an astronaut about to launch. During the years of preparation for Project Mercury, the unknown areas have been shrunk, we feel, to an acceptable level. For those who have not had the advantage of this training, the unknowns appear huge and insurmountable, and the level of confidence of the uninformed is lowered by an appropriate amount.
All the members of the Mercury team have been working towards this space flight opportunity for a long time. We have not dreaded it; we have looked forward to it. After 3 years we cannot be unduly concerned by a few delays. The important consideration is that everything be ready, that nothing be jeopardized by haste which can be preserved by prudent action.
So there's your recipe: want to reduce fear, increase knowledge. That's not just wisdom for Astronauts.
The entire Mercury 6 report makes for fascinating reading, and includes the audio transcript of the entire mission.