The next time you need to jockey a bulky door into position, save your back and use one of the oldest and simplest tools: the lever.
Place a small wood block on the floor about 2 in. Away from the door—it will act as the fulcrum. For the lever, use a flat pry bar. Lay the bar across the wood block and slip its end under the door. Then, simply press down on the bar with your foot to lift the door, using both hands to guide the door into place.
If the lever doesn't raise the door high enough, use a thicker fulcrum. This technique can also be used when installing heavy sheets of drywall, cement board or plywood.