Hindsight is 20/20, as they say. It would be nice to know for certain that whatever it is you're worrying about will pass with time and that everything will be a-ok in the end.
One of my favorite pieces of advice I've ever received (and I'm ashamed to say I can't for the life of me remember who it is who shared this nugget of wisdom with me) was this:
Most of the time, the answer is no and while it's easier to say that when you aren't in the throes of anguish and worry, it's something good to keep in mind to put things in perspective. Most things simply aren't worth losing a huge amount of sleep over and the majority of the time, everything works out in the end.
Came across this on another blog I follow and I loved. Enjoy!