CORAL GABLES, Fla. — On a rooftop parking lot, with temperatures in the chilly low 50s, a crowd of all ages shimmied and shook, sweated and smiled as DJ Francis played an eclectic mix of dance music.

ALTHOUGH I’VE tried organized dance a number of times, I usually feel like a donkey on the dance floor. I have a severe aversion to looking stupid. So when I decided to take my first Zumba class, I ...