Even with an exceptional idea, budding entrepreneurs can struggle to move past the brainstorming stages. They face challenges in execution like building a cohesive team, coming up with a business plan and even understanding how to present their product or service.

This week mentors on WSJ Startup of the Year, a documentary on WSJ.com, offered some words of inspiration for all entrepreneurs. Here’s what some science and technology innovators had to say. Edited excerpts:

Ray Kurzweil, director of engineering at Google: “Ninety-five percent of the innovators I meet would actually do exactly what they say if given the resources, but most of those projects would fail because the timing is wrong.

“A lot of business and technology plans assume the world three or four years from now will be kind of like it is today, and that’s not the world you need to aim at. That’s going to be a completely different world. The world is completely changed in just a few years time, and it will change at an even faster pace in the future.

“So a key harbinger of success is to actually understand this exponential pace of change and make your project relevant for the future world and meet the train when you get there.” […]