Exceed expectations. Super helpful. Choose to make an extra effort. Imagine getting a vehicle ride from someone and even though they are going in a different direction, they will go out of their way to take you to your destination. ‘Out of their way’ implies that someone wasn’t planning on doing something, but has decided to do so as to be helpful to you. (Compare to Go the extra mile.)

“You want me to stay for dinner? How nice, but don’t go out of your way.”