This exercise conditions deep core muscles in a risk-free environment while also improving coordination and the connection between body and mind. Lie on your back with knees bent, and lift feet and arms from the ground so that knees are above hips and hands are above shoulders. Slowly straighten one leg so that it is just above the ground without touching it. At the same time, lower the arm of the other side of the body above your head. Bring them both back in, and alternate to the other arm and leg.
It is normal to lose coordination for the correct arm and leg. If that happens, just return to start, reset, and begin again.