Divide the group in pairs. Each pair is going to count to 3 together in the way: player A: ‘1’, player B: ‘2’, A: ‘3’, B: ‘1’, A: ‘2’, B: ‘3’, A: ‘1’, … etc.
This will prove harder than it seems. The difficulty can be increased or decreased, depending on the player’s experience, in the following way: A player saying ‘1’ has to jump, when saying ‘2’ they clap their hands and when a player says ‘3’ they shake their butt. Afterwards, ask the players if they experienced this as more or less difficult.