How Can Disappointments Have a Good Side?

Have you ever encountered a disappointment and been unhappy for a long time? Well, maybe you shouldn't have been that way, because disappointments can have a good side. For example, if you learn from them, disappointments can be good. In addition, if they help you in the long run, like finding out that your best friend is going to a different but worse college than you because he didn't make it into your college.
Disappointments aren't always bad. Sometimes, they help you more in the long run than they make you sad. Also, disappointments are a good learning opportunity, to make sure you never make the same mistake twice.