Kind of hard to explain but I have found that a longer stroke works better than a harder one. Sit on the garage floor in front of a 2x4. Raise the hammer high above your head. Whack the hammer on the 2x4. Seems like it works better. 3-4 strokes at most.

Momentum? Inertia? Physics was a loooooong time ago and I don't remember which one this falls under