AURORA, Colo. — William Harris tapped his retirement savings to open A-Town Pizza, a Neapolitan pizzeria, in this Denver suburb three years ago. He borrowed $200,000 to open a second location this year and now employs 60 people. On a good Friday, his shops sell 1,200 pies.

In such stories, the Federal Reserve finds evidence that its seven-year campaign to reboot the American economy is succeeding. So on Wednesday, the Fed, which has held short-term interest rates near zero since December 2008, will most likely announce that it will start nudging rates upward, slowly ending what has amounted to a once-in-a-lifetime sale on money.

Mr. Harris, for one, is not ready. “It’s scary when you hear that the government is planning to slow things down,” the wiry 39-year-old said as he folded menus. “We live on people’s extra money. That’s the money they spend on pizza. And it still feels very fragile.”

Monetary policy is conducted in a language of bloodless abstraction, and most Americans pay little, if any, attention. But the Fed is about to make a big bet, and the decisions it makes in Washington have large consequences, here in Colorado and across the nation.