New York (CNN) - Jeff Parness still remembers the pain of September 11, 2001, when his friend and business partner, Hagay Shefi, was among the thousands killed in the World Trade Center attacks.

But Parness, a native New Yorker, also hasn't forgotten the support that his hometown received from other communities in the immediate aftermath. Many cities - in the United States and around the world - sent volunteers and supplies to aid the rescue and recovery effort.

"9/11 changed all of us forever, but 9/12 changed us just as much," said Parness, 45. "That outpouring of kindness and generosity, to me, was more powerful than the terror that happened the day before."

That spirit of goodwill inspired Parness to create New York Says Thank You, an organization that sends volunteers from New York City to disaster-stricken communities every year - normally around the 9/11 anniversary. To date, more than 7,000 people have participated in the group's rebuilding projects.

Running a nonprofit isn't something that Parness, a former software venture capitalist who lives in Manhattan, ever thought he'd do. He had never been community service-oriented. But a suggestion from his 5-year-old son changed all of that.

Read more on Parness here.