Launching a startup is hard—really hard. It’s a journey filled with rejection, second-guessing, and disappointment—and that’s if you’re lucky. So when do you walk away?

After nearly two decades climbing the corporate ladder at blue-chip companies—the last decade working in education—it became obvious to me that something was missing in the market: an easy way to curate and integrate materials from around the web and turn them into complete college courses. I spoke to friends, colleagues, entrepreneurs, investors, and others who agreed that there was likely an opportunity unfolding—one that could turn out to be quite profound—but still no one was going after it. So after careful consideration with my family and a trusted long-time colleague (who became my cofounder), I made the leap into the great unknown.

One thing you learn very early in startup-ville is there are 10,000-plus reasons why what you’re doing won’t work, won’t scale, won’t be profitable, won’t be defensible, etc., and there’s no shortage of people who will let you know. But if you’ve done your homework and spent hundreds of hours with prospective customers to understand their needs and pain points, you know something that all of them don’t know—that you’re right. We spent our first three months doing intensive research with faculty and students and found that even though faculty were still assigning textbooks, students weren’t buying them as often, and preferred to turn to YouTube and Google (GOOG) before flipping open those heavy tomes in their dorm rooms. So in spite of all of the negativity and rejection (of which there is plenty), you have to stay true to your ideas while staying focused on the only audience that really matters: your current and future customers. If you can solve enough high-pain problems for them in an easy-to-use way, the world will start to catch up with you, but if and only if you survive the grind.

See also: This Is Why So Many Startups Aren’t Successful

For every Snapchat, Instagram, or Facebook (FB), there are thousands of other companies that eventually realize success isn’t likely to be immediate. Sure, that makes great reading here on Fortune or TechCrunch, but that often isn’t the way success happens. It’s about persistence and fine-tuning, changing sales tactics, adjusting pricing, modifying marketing messages, tweaking product UX and UI, and getting the right team in place all to get to the magical mix that starts bubbling and frothing into what can become a successful business. Junction Education is our second name (the first—edRNA—proved, ahem, challenging), we’re on our third website and second approach to selling, and it’s finally all coming together.

It might not be exactly what you dreamed it would be when you started, but that’s okay. Insight and experience accumulate over time, and successful founders are always learning about their markets, their competitors, their staffs, and themselves while figuring out how best to adapt or pivot when necessary. In our journey with Junction, we’ve made a few pivots—from direct sales to faculty toward institutional licensing, from open educational resources (OER) only toward a mix of OER and licensed content, and, our first big change, from tablet only to web first, tablet optional. Each pivot enabled us to take the next big step forward in growth.

Evolve and survive with a chance to thrive or stop and reset. If you can manage the former, and are close enough to nailing the magical mix, keep on going as long and hard as you can. But if you know, I mean really know, that the road isn’t going anywhere, then pull over, get out of the car, and take a moment to admire where you’ve come before turning back around. I guarantee it’s worth it either way.

Vineet Madan is the founder and CEO of Junction Education, a company working with colleges and universities to deliver affordable, engaging and effective learning experiences.

Read all responses to the Entrepreneur Insider question: How do you know it’s time to drop your startup idea?

Your Personality Could Be the Reason Your Business Is Failing by Suneera Madhani, founder and CEO of Fattmerchant.