So many buzzy new workouts, so little time. But we promise, Orangetheory Fitness deserves a spot near the top of your list of sweat tests this year for its smart system and crazy calorie burn.

While it’s not brand new—Orangetheory is close to celebrating its sixth anniversary with more than 330 studios in 28 states, and more overseas—the company only recently opened in big cities like New York and Los Angeles. And it has quickly become a known name (and color) in even the most competitive fitness-focused metropolises. (According to Google, it was one of the 10 Biggest Workout Trends of 2015.)

The model is smart and simple: Enthusiastic, experienced instructors plus a heart-rate monitored cardio and strength session equals max results in just an hour. Here’s everything a first-timer should know before joining the “orange nation.”