That word people struggle with saying is “no”. 

If you really think about it, it’s one of the first words we learn to say. The first three words uttered out of most babies mouths is “mama”, “dada”, and “no”. They say it to everything. Try to take something from them, they’ll certainly yell, “NO!” Try to make them eat something they don’t want, they’re going to scream, “NO!” Try to put them in the bed when they are fighting sleep, issa “NO!” 

Somewhere along the way, most people develop a people pleasing habit and lose that “No”...