I tech screened a tester this morning for a position on my team. I always ask the candidate to describe the tester mentality. I loved today's interviewee's answer:

More than the product working perfectly without any crash assert, if it is not intuitive and user friendly it is useless. What will the customer use it for? Does it provide value for the scenarios the customer cares about? Think of the variety of customers - not everybody will have a top-of-the-line machine, or the same technical expertise, or the same expectation of the product. More than just breaking software, the tester should make sure it has the capabilities the customer needs.

Right on! This is what our automation stack is all about - keeping that customer focus.

If you aren't thinking about your customer, keeping them in mind as you test, then you aren't testng.