This is a great clip of Chen Bing teaching a basic silk reeling circle with a lot of emphasis on relaxing and being heavy.
People often wonder how being relaxed can generate power in martial arts. If you watch the video you can see how being relaxed in the upper body leads to great power in the lower body. And once you have that power in the lower body you can start to use it to drive your movements. Of course, there’s more to it than that, but it’s a start.