Making very small movements is difficult initially. In modern society, our bodies are not encouraged to make small, smooth, controlled movement. Everything is jerky and abrupt.
Jerky movement agitates the nervous system and this in turn leads to anxiety and a lack of calm.
e.g. if you simply flick the wrist, the joint is not exercised properly but if you move the wrist extremely slowly, you feel a very notable stretch throughout the entire movement.