The biggest realisation for anyone while working is to know that they are NOT the customer of their product.

Which means, to have an empathy to understand what the customer needs.
What are their pain points.
What makes them happy.
What mood they are in, while they are using your product.
What is the feeling they want to feel, when they use your product.

The more you distant your apprehensions from the questions of the customers and go deep into the latter, the more you get closer to their hearts.

Empathy is what builds a customer. And make them stay.