The present invention is a boomerang flying toy having a plurality of blade arms with airfoil-like tapered perimeter edges along their respective cut lines to give the boomerang toy improved aerodynamic performance characteristics. A first lens group includes a first positive lens having a meniscus shape and having a convex surface on an object side thereof, a negative lens arranged on an image side of the first positive lens and having a concave surface on the image side thereof, and a second positive lens arranged on the image side of the negative lens and having a convex surface on the object side thereof. The present invention has the advantages of decreasing the force required by the muscles during the exercise as well as retarding the impact enforced thereon while the user is jogging or exercising. The apparatus for indicating the direction of change of direction of the mobile device is one of a gyroscope, an accelerometer, an electronic compass, the GPS or a device determining direction based upon the magnetic field of the earth.