Make 6 or 8 columns of players (at least 2 in each column).
They will have 2 balls in play, with some time distance. (wait until the first ball reaches the middle point and then the second ball starts being passed around)
The players will have to pass the ball and run to the column they just passed the ball to.
They will have to be running when they pass the ball, and change passes after a while (normal, bounce, side, underarm,...)