ON Monday, inside a warehouse turned gymnasium on an empty street in Gowanus, Brooklyn, a group of well-educated, accomplished New Yorkers chose to start their holiday with one of the most punishing workouts on earth.

That workout, bluntly known as Murph, is as simple to explain as it was difficult to complete: a one-mile run followed by 100 pull-ups, 200 push-ups and 300 squats, followed by another mile — all for time. No picnic, and yet by 10:30 a.m., the gym was swarming with social workers and food bloggers, as well as F.B.I. agents and former Marines, who grunted and sweated on the rubberized floor mats as a life-size statue of Yoda presided from a platform nearby.

To make things interesting, a few men — one of whom confessed to being slightly hung over — did the entire workout in 20-pound weighted vests. Others performed modified versions: reducing the number of pull-ups, for example, or doing the push-ups on their knees.

Everyone, however, appeared to be suffering.

“That was an hour of pure torture,” said Peter Hoppmann, 50, a seventh-grade history teacher, who was drenched in sweat after completing three-quarters of the Murph in 55 minutes and 36 seconds. But he was smiling as he said it.