I don't really use set weights, I use water bottles. So I started with a water bottle in each side that was 1/4 full. I also didn't up it in set increments, I waited until I could see Squirt's stamina improving. At first you could tell that it was much more tiring on our walks, but slowly he was able to walk longer without pooping out. So I just increased them to 1/2 full after I noticed a big difference in stamina, then again to 3/4 full, and now we use 2 full water bottles. I could probably increase it to small barbells or something but 2 full water bottles works fine for us. Hope that helped