Gym Pod and Kai Xiang Teo The private gym-in-a-box concept is so popular it's now expanding across the world. I balked at the price at first but came to love it as a space for working out without anxiety. Now that I'm further along in my fitness journey though, I can't quite justify the price of using it regularly. The private gym in a box is a concept that's popular and going global now, but it began in Singapore.