I just wanted to let you know that weight didn’t seem to be a factor in instability with my walker, I is edit as soon as I was able to get out of bed, the day after surgery, and right up until about six weeks after surgery. I was VERY unsteady with it at first, and you are correct- the motion required to use it is exhausting, no matter your size. Just make sure to get up as often as you can manage, laying in bed all day is counterproductive. If you work at it, I promise you will get tired less quickly. And the soreness in your hands from supporting your weight on the walker will go away too. I had that as well and I weigh 140 lbs. hang in there- you can do this- I promise.