The above link was first accessed through Janet Reid's blog. If you're not following Janet's blog, well . . . start following. It is a source of great information. The web is full of sources of great information. Yeah, sometimes you have to slog through a ton of crap to find the diamonds, but it's definitely worthwhile.
The above link is a must read. It's an eye-opening experience kinda read that has just started my day off right. Okay, Starbucks actually started my day off write, but the above blog link is coming in at a close second. The post is all about when to quit following your dream. There is, of course, a Susan Boyle mention (quite a few paragraphs in fact), because what are dreams without the mention of Susan Boyle? She seems to personify the tenacity and spirit of dreamers everywhere. I'll leave the rest of the explanation to the above link. Read, enjoy, and learn.