Henry Reininger is a 72-year-old accountant who escaped the Nazis in Austria and spent most of his life in New York City.

He’s grooming his daughter and 10 grandchildren to take over the business, with his 10-year-old grandson “particularly enthusiastic,” according to the New YorkTimes, which offers an interesting flash demo of Reininger’s story.

To this day, the accountant eats breakfast and dinner in his office and sometimes can be found there at 2:30 or even 4 a.m. if that’s when his clients need to meet with him.

His secret: One good night of rest (Friday night).

Thanks to Rick Telberg of CPA Trendlines for passing on the story. It can be found here.