Forgetting your password presents you with a great opportunity to try and see what's entailed with trying to break into an account. You know pretty much everything there is to know about your target (you) so you can make educated guesses about what kind of password it might be, whether there are dictionary words involved, what kinds of numbers or symbols are likely to be used, etc.
Unfortunately, you usually only find out you've forgotten your password when you really need into the account and don't have time to mess around with all that. However, if you ever find yourself with the time, do try it and and see how well you do.