Our daily lives have a strange manner of smothering us with stress and worries in various forms and shapes. Looking back, we may discover that many of the things that we were worried about were truly not worth the distress that they caused us. This does not mean that those situations and experiences were actually worthless. Instead, this means that we have learned and improved ourselves so that in the future, we can weather similar situations in a better manner. Thus, they no longer seem frightening or stressful.
Charles Darwin famously posited that only the fittest members of a species are capable of survival.