I used to attach a towel or a dive mask to my leash for more resistance on paddles. Used to do it on a 7' fun shape before hurricane season each year, now I just paddle a long board, no damn resistance, too much work for this old dog. It still feels great, on a flat day, to drag a long leash, and when I get tired of paddling, I can put on some goggles, and drag the board while swimming and diving the shallow reef. It works different muscles and the zero gravity gives your ribs a break. Then you can paddle some more.