There are several very reasons that Fitness Blender has become the most popular fitness channel on YouTube. There is no screaming, no threats, no loud music, and no super-pumped egomaniacs showing off their bodies. In fact, most of the more than 500 workouts were filmed in the garage of Fitness Blender founders and trainers Kelli and Daniel Segars, two real people who look like real people, although very fit real people. Most of the workouts require only a set of dumb bells, and yes, they are free. As the Wall Street Journal reports, Fitness Blender doesn’t depend on the sale of nutritional supplements, the suspect business that keeps many fitness sites afloat. The channel lives on video ads, plus digital eating plans and workout plans that sell for $6 to $25, sufficient, apparently, to turn the the seven-year-old venture into what the Segarses say is a multimillion-dollar business with revenue growing more than 20 percent a year.