I have to disagree somewhat on this. I think the best product managers put themselves into their customers shoes, and solve *the customer’s* problems, and test from *the customer’s* perspective. That is, empathy (which is probably elsewhere on this list) is the really critical thing. My lesson on this was when I was the product manager for Accept360, and my customers were *product managers!* When talking to them I *always* learned about perspectives I didn’t have, even though my customers and I had the same job, often in the same industry. Even though I was a daily user of my own product, I still needed to step outside myself constantly to assess what we were doing and why.