Of course it is. Because life throws many curves at us every day. But much depends on our expectations. If we have high expectations, like making a million dollars right away, then we become disillusioned and disappointed when it doesn't happen. Some people on Hub Pages, for example, get upset because they don't make much money from AdSense, etc.
So the trick is to keep the expectations realistic. And also realize that many people have it worse than you do -- regardless what happens.