He Went From Showing Strangers Photos of His Idea in Bars to Selling 100,000 Units Nationwide — Here's His Secret to Valuable Feedback Learn how this co-founder moved beyond friends and family for honest product feedback and why his approach could help you validate your next big idea.

So, you have an idea for a new product. You think it's good — but how can you really tell if people would pay for it?

If you're starting out with little to no money, testing your product effectively can be tricky. You need to know if it's market-ready and if there's strong consumer demand. Asking friends and family for their opinions might seem helpful, but they're likely to be too soft on you.

Mike Mayer, co-founder and co-CEO of Windmill, faced the same challenge. He launched his business with just his brother and a close friend. Today, their product — high-quality AC window units, referred to as "the iPhone of air conditioners" — is now selling 100,000 units in every U.S. state.