How to know when it gets too much

I sometimes find myself falling in the rut of thinking I'm Superwoman and can do it all. Regardless of a project, I tend to think that I don't need help (even when I do) and suffer through the painstakingly horrible task of trying to get everything done, and although I do, I could save myself a lot of trouble by just asking for help. I try to get my clients to see the light, especially from experience, that they can't do everything and that trying to tackle the small pieces before finishing the big picture. When looking at a puzzle of your dream business, project, goal, it can be very convincing to try to jump in head first, but take a breath, know your limits and learn that it's okay to take a break and recognize when something is too much for your plate.