You are solving the problems that other people face. In order to truly understand those problems, you need to put yourself in the shoes of others-- to empathize.
Design is human-centered
YOU CAN'T ASSUME HOW YOUR CUSTOMERS THINK AND BEHAVE.
GO OUT AND ASK PEOPLE ABOUT THEIR LIVES, AND FROM THOSE CONVERSATIONS, UNDERSTAND THE PROBLEMS THEY FACE.
Family and friends aren't objective because they care about you. Talking to strangers is essential because they will be more honest and blunt.
Start by asking your interviewee a broad question, and then keep responding to their answers with "why" until you have a deeper answer.
Stories will tell you far more about a person than one sentence answers. Start with "tell me about a time when..." or "when have you felt most..."