The theory behind this exercise/tool is that it
syncronizes brain hemispheres. (Cross crawl and hookups are thought to
do that also,)
It has a calming effect and reduces, even
eliminates feelings of anxiety. One man experienced anxiety whenver he
got in his car and tried to drive to work. He found that if he pulled
over to the side of the road at the first sign of anxiety and tossed a
small ball from hand to hand, as if he were juggling, the anxiety would
pass.
So, he drove to work, stopping frequently to toss the
ball. On subsequent trips he did the same, and found that he need to
stop less and less to do that, and quickly not at all.
You can make your own ball by using a pair of sox and nesting them into a round ball-like object.
Just toss the ball back and forth between your hands.
You could also learn to juggle, which I'd think could be even more effective.