Do you use a portable ramp because of your knees? Need help

Those concrete blocks are h-e-a-v-y! You can get 2'x2' Plywood squares from Home Depot or Lowes and screw 2x4 sections to them to get 2" high or 4" high platforms depending on which way you turn the 2x4s. I'd put one across the center as well as those on the perimeter. Paint them to last longer and mix sand with the top surface coat to make them non-skid.