Paraphrasing a quote: As soon as we stop losing sleep over the success of our business, and start losing sleep over the success of our customers' business, then we will find success.
If all we are selling is our own product / solution / service, then that is where our focus will be - our selves. But what really matters is whether that resolves a problem for our customers - even a problem they didn't know they have (a la the original iPhone). What is it that limits our customers from doing what they need to do? How could what we do significantly remove that limitation? How would that impact them?
I heard this quote on a recent People and Projects Podcast from Andy Kaufman. He had similar things to say about it, along with another quote in the brief podcast. He attributed it to reading a book by Don Miller. (I'm guessing it's Donald Miller's Creating a StoryBrand.)