The following post was inspired by a breakfast conversation I recently had with a successful entrepreneur:

If there’s a single thing you should take away from business school, it is to ignore sunk costs If your company is going nowhere, cut your losses and move on.

There are three things that could happen to your company: 1) It can succeed by going IPO, getting acquired, or by making a modest profit. 2) It can fail. 3) It could go nowhere. The absolute worst thing that can happen to for it to go nowhere. Few thoughts:

Firstly, it’s widely agreed that entrepreneurship is best while young. You’re the most ripe for doing business from the second you finish school up until your mid-late 30s because you have less to lose. At a younger age, you’re more connected to what’s going on in the industries you’re associated with. If you start a company in your early 20s and the company drags on for more than a few years, you’re wasting precious time. If you don’t see lots and lots of growth or if your company’s not bringing in cash, cut your losses within a few months of starting the company and move on to the next opportunity.

If your company lacks a business model, yet it continues to grow, you should have the option to sell out. Matter of fact, you should probably think long and hard about selling such a business after two to three years of working on it. If you had a serious business model that proved to be effective, this would be different. Given that the company is (supposedly) growing, you’ll probably be getting acquisition offers left and right. What’s important is that you always have the option to sell. The discussion of selling a company will vary from person to person. There is no correct way to do this, because while some entrepreneurs prefer to exit early, others prefer to create businesses for the long term.

Remember when Mark Zuckerberg was offered billions by Yahoo to sell Facebook? Many of us critiqued him for not selling, because the future of Facebook was unknown. Most of us would kill to sell our company for even a few million! But his reasons for not selling probably weren’t monetary related. If Zuck had $2B VS $20B, the course of his life wouldn’t change all that much. He wants to build a true business for the long run, and selling out to yahoo would be premature. As long as Facebook continues to grow, he has the option to exit.

For other companies that either aren’t growing or aren’t finding a way to exit, cut your losses sooner rather than later. If you start a company and within three months, you realize that you don’t click with your co-founder, get out. He or she is wasting your irreplaceable time and energy.

Even if you know that it’s time to get out, it can be incredibly difficult to sell. After all, you’ve been growing your business as if you were raising a child. Sending your child to college is always difficult — sending your child to college years before the average child goes is even more difficult. I see selling businesses in a very similar light. It’s different from person to person, and when the time is right, you’ll know when to exit.

Jessica Mah is a 17 year old entrepreneur, blogger, and sophomore at early collegeBard College at Simon’s Rock.

She loves chatting with fellow students, readers, and entrepreneurs, so don’t hesitate to email her or message her on AIM! Feel free to subscribe to her blog or stalk her twitter.