"It's not just a good thing to be involved," he said of community service. "It's a requirement."
Bernstein started the Philadelphia area's King Day of Service in 1995 with 1,000 volunteers - mostly Philadelphia schoolchildren and Americorps volunteers.
It has since spread to cities around the country, and this year's projected turnout in Southeastern Pennsylvania and South Jersey - more than 85,000 - would be the largest in history.
Last week, Bernstein's efforts won him recognition from President Obama, who honored him as one of eight White House Champions for Change for embodying King's legacy.
Harris Wofford, the former Democratic senator from Pennsylvania and a leader in the civil-rights movement, credits Bernstein, a former aide in the 1990s, as the first person who thought Martin Luther King Day "should be a day on rather than a day off."
After Wofford, who led the charge for the law that made King's birthday a national day of service in 1994, lost his Senate seat to Rick Santorum that year, Bernstein began working to become, as Wofford put it, the "foremost driver of that idea on a large community scale."
So how did a white Jew from northwest Philadelphia become the best-known champion of a day devoted to remembering King?
"It's not always been . . . welcome by everyone," the 54-year-old Bernstein admits. "But it makes perfect sense to me."
Bernstein attributes his interest in public service to a 10th-grade trip he made with classmates from Abington Friends School to Scranton to help clean up after Hurricane Agnes in 1972, at the time the costliest hurricane to hit the United States.
We were "literally knee-deep in mud in someone's living room," he remembers.