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I have found such fear to often be wrong. In most cases, what I worked up to be a big deal turns out to be routine and nobody cares. And even when things don't go well, they're not as bad as I imagined.

It's OK to prepare for the worst while expecting the best to occur; this is what allows for peace of mind. What isn't OK is worrying about things over which we have no control; that leads to fear and madness. Prepare first, then act.