Where would the good days feel like, if there weren't any bad days that made us appreciate them?
Sure, bad days suck for everyone. However, we need a little bit of drama in our lives to make life interesting, to have something to laugh about later. It may seem bad now, but it'll be a great story to tell in the future.
And a little reminder to those who are having a bad day, week, or year -- things will get better.