When I was a mechanic we would do engine runs in the middle of the night on beater Cessnas, huge torch in hand, checking for oil leaks after maintenance. I would ALWAYS have one hand on a strut, and if I couldn't see the front of the engine using that method then so be it. The scarest part was adjusting the carb idle screw while that puppy was running.
One time at a remote airfield I had a dead battery in a Cessna 150. I was deciding how I would hand prop it without anybody around to hold brakes when an old grizzled IA drives up out of nowhere and offered to help. He told me to get inside and hold the brakes while he tried to hand prop it. After a while he was unsuccessful, so he pulled up his car and jumped the battery.
But in order to get the battery box lid back on, this old grizzled IA withstood the mighty wind forces the O-200 was producing and stuck his hands in the tiny access panel to pin it in. The angle was screwy, so he was gyrating all over to get it in, bringing parts of his body within inches of the blade. I was holding the brakes like mad. He eventually was successful, gave me a slight nod, jumped in his car and drove away, leaving me alone with the weeds and coyotes to contemplate life.