The flashlight you carry on early morning runs almost didn't exist.

Or at least, not in the form we know today.

An LED—short for light-emitting diode—is a tiny semiconductor that turns electricity directly into light. They’re far more efficient than old incandescent bulbs because they create light instead of mostly heat. At a basic level, they work by moving electrons from a higher to a lower energy state, releasing a photon of light in the process.

For decades, engineers could make bright red and green LEDs. Blue was the problem.

Why? Think back to ROYGBIV—the colors of the rainbow. Red and green light are lower energy than blue. It was much easier to build materials that could produce those lower-energy emissions. Blue required a bigger energy jump, and that proved far more difficult to achieve.

That might not sound important until you realize that without blue, you can’t make bright white light. No LED light bulbs. No modern phone screens. No energy-efficient flashlights.

Scientists knew the material they needed: gallium nitride, a compound made from gallium and nitrogen that, in theory, could produce the high-energy light required for blue. The physics checked out. The problem was that it refused to cooperate. The crystals were full of defects. They cracked. They wouldn’t produce bright, reliable light. Many of the smartest researchers in the world eventually concluded that practical blue LEDs simply weren’t possible.

Then there was Shuji Nakamura.

For years, he looked like a failure. He wasn’t at a prestigious university. He worked at a small company with limited resources. And for a long time, he had little to show for his efforts. His colleagues doubted him. His superiors encouraged him to move on.

Instead, he kept going.

He got angry. Then he invented.

He took every bit of doubt, every dismissal, and every setback—and turned it into fuel. When leadership told him to stop, he didn’t quietly accept it. He kept experimenting anyway. He refused to let the problem go.

Thousands of attempts. One variable at a time. And eventually, one of those tiny changes worked.

His breakthrough made the first practical bright blue LED. That unlocked white LED lighting, which has since become one of the most important energy-saving technologies in history. Today, LEDs light our homes, our cities, our cars, our televisions, and the screen you’re probably reading this on. In 2014, he was awarded the Nobel Prize in Physics.

Most people think persistence is calm. Patient. Sometimes it is.

But sometimes, persistence looks like something else entirely. Sometimes it looks like frustration. Like stubbornness. Like refusing to let something go.

When you’re frustrated, there are a few paths you can take: you can give up, you can hide, or you can fight.

You can let it stop you. Or you can use it.

Happy running.