Gone are the days when hitting a workout or yoga class entailed major scheduling drama, paying monthly dues or a per-class fee and sweating amongst a big group of sweaty strangers. According to YouTube, more and more people are bringing their workout home by streaming fitness videos and that ‘last year, viewers watched 5,500 years-worth of yoga videos alone.’ While this new trend may be appealing for the sake of convenience and the luxury of choosing from endless instructors and classes, Carol Garber, a professor of movement science at Columbia University warns to be wary of online instructors and to check their credentials before engaging in one of their workouts. But also, keep in mind: Several studies done over the years have supported the theory that group exercise is a more effective tool for weight loss than solo sweats. Though a cyber group may give you the feeling of being in a class, you won’t have the same mental peer pressure to succeed as you would if you were surrounded by real people—nor an instructor to push you and to correct your mistakes, which could also increase chances of injury.