Moving anything requires a bit of a warmup and even moreso as we get
older. Expecting to climb out of the pickup or off the sofa and be lifting
shallows or deeps is
inviting trouble. Take a minute to loosen up your back before any lifting.
   One thing I find that helps me is to screw decent handles onto the sides
of the boxes and to bring a few empty boxes to set things on so that I am
working at an efficient height.
    All of my beginners have begun on medium boxes.