To expand on this, when you're a kid, things that affect you emotionally can seem to have disproportionate impact on your life. When you're older and more experienced, you've been through many crisis situations, and you've seen that things usually work out OK. You know better how to deal with various situations, and you have a much more realistic predictions of how things will eventually unfold.

You probably also know, from experience, that even if you have an initial emotional reaction to something, that doesn't mean you should trust those emotions and roll with them. Getting angry rarely fixes anything, feeling sad is normal but it doesn't mean your life is going to shit, and getting excited about something is good, but you know it might not be worth getting excited too quickly.