If you're a young, aspiring entrepreneur who is a little overwhelmed getting your business off the ground, you've probably fantasized about finding the perfect mentor. This seasoned pro would recognize your potential, introduce you to the right people, set you on the fast track to success and, let's face it, boost your ego and your confidence.

Entrepreneurs' daydreams of this nurturing, Yoda-like mentor may be as natural as school girls mooning over Justin Bieber, but it's still entirely wrong, according to a recent post on the HBR blogs by author and training pro Jodi Glickman. In it, Glickman, references Patty, the merciless voice coach on American Idol, and suggests that what young folks with start-up dreams really need is a mentor who scares the bejesus out of them:

As a rookie, you're not necessarily supposed to know anything, anyway. All you've got is your good attitude, your enthusiasm and a strong work ethic. And when you're new to a job, people expect you to have bumps and bruises along the way as you move up the learning curve. You also want to take that drubbing now so that you avoid it later on (when your ego takes more of a bruising, when the thought of an 80-hour workweek and simultaneous childcare makes your stomach turn, or when you think you're simply too old to take that kind of treatment from someone else). So take advantage of that early grace period and test the waters, take risks, put yourself in harm's way so that when the stakes are higher and you're not allowed to mess up, you're uber-qualified and up to whatever task comes your way. You don't need to be a masochist to really get out there and try your mettle — and learn a lot.

I had a Patty of my on early in my days on Wall Street, and I can't say enough about how much I learned under his tutelage. His name was Will and he was whip-smart, utterly unflappable, relentless, standing out from all of his type-A overachiever peers at our investment firm…. As scared as I was of subjecting myself to his intimidating brilliance, I think I was more terrified of not being able to hold my own with him — what would that say about my own future in the hard-knocks world of Wall Street?

So I decided to take my pain early and learn as much as I could from the master.

Getting fit for start-up life, as Glickman describes it, sounds a lot like getting fit for a boxing match. Take your pain in small controlled doses now, or take a far worse beating later on.

And there are other experts who would back her up. Justin Menkes, the author of Better Under Pressure, has described learning to handle pressure as akin to learning to handle physical stresses, requiring incremental increases in the demands we put on ourselves. But each new challenge, he stresses, needs to make you a bit uncomfortable.

"You have to build inside your brain, your consciousness and your stomach a knowing that you can handle it," he said. "Put yourself in situations that elevate your sense of stretch."

One way to do that: face off against a tough mentor that intimidates you.

Are scary mentors a good solution for everyone or only for certain personality types?