I asked earlier about weak ankles, and a few of you mentioned sled dragging.. Just got a couple of question for those of you who do sled drags. -Did you just end up buying a sled from elitefit or did you make you own? -Did you find any noticeable differences in your bodie's performance after starting sled dragging? Acceleration, explosiveness, endurance/stamina increases? --additionally, could someone point me in the direction of building a sand bag?