A human will tend to resist any change about which he has not been consulted.
That’s it.
Don’t make changes — no matter how beneficial — which will affect another human, without first saying something like “I notice that your car is broken. I could fix it for you. Should I?”. Exceptions? Sure. Buy your girl a diamond bracelet; probably things will work out. But generally, consult first, then change stuff. Everybody happy.
Even if you already know what you’re going to do, ask them for ideas first. Even if, when consulted, they claim your desired change is a terrible idea, you will still get better acceptance if they’ve had a chance to say. (At the very least, they’ll feel satisfied that they told you so!) Take it for a test drive; you’ll see.
Knowing this important secret of the universe, go forth and prosper.
