The initial push against a heavy vehicle that is at a dead stop is tough but once you get started, the faster you push the vehicle, the faster the wheels roll and the easier it gets.
Measure out a 100-foot flat course.
Set up at the back of the vehicle with arms extended and palms on the rear bumper. Your feet are shoulder-width apart, knees slightly bent. Have a friend put the vehicle in neutral, steer, and time you.
Lean in hard to the vehicle to start the push.
Switch over to a normal running pattern (i.e., one foot then the other).
Keep the head up and the arms straight so that you can transfer more leg and hip drive into pushing the truck.
Stay low and move in a straight line.
When you've hit 100 feet, have your friend brake the vehicle as you run to the front of it. Now you get to push it backward while you sit on the bumper. Extend the arms back so that the hands rest on the bumper.
Extend the legs one at a time to push the vehicle backward. If you feel the quads on fire, you are doing it right.