The present invention provides a compact, portable, centripetal force-driven exercise device. The device employs a handle equipped with a rotational member. One end of a strap is attached onto the rotational member; the other end to a soft bag. The soft bag, preferably of a heavy duty cloth or synthetic fiber construction, is capable of holding one or more water-refillable, reclosable plastic bags. The strap can have adjustable length. The soft bag itself is also capable of being filled with a desired amount of water. The handle preferably is covered on its exterior surface with a hand grip material. The user places the desired amount of contained water weight into the soft bag, holds the handle and swings the bag in an orbital pattern at a desired number of revolutions per minute to achieve the desired degree of centripetal force resistance to exercise, strengthen and condition the user's muscular system.