CPR training teaches you to press much harder than feels polite. Sometimes doing it right feels wrong at first.

Doing something right sometimes overrides the instinct to be gentle. Compressions have to go deeper than feels acceptable, because the polite version does nothing and the hesitation is the real danger. Plenty of correct actions feel wrong at first, especially the ones that involve pushing, interrupting or saying something blunt. Comfort is a poor guide in a situation you have trained for.

Trust the training over the feeling when the moment comes. If you have never done the course, look up a local one, because the right amount of force is not something you can reason out on the spot.