I really liked John Galloway's post on The Man who Knew Too Much, in which he outlines the wrong assumptions and actions we can sometimes make/take when surrounded by smart people, being too busy, etc.
However, the item that caught my attention was his link to the strategy of aspiring to be the dumbest person in the room (it's about 2/3 the way down the page in Sally's answers) – that is, surround yourself with really smart people. It gets us out of our comfort zones and challenges us to contribute to greatness.
One of my favourite expressions (and greatest irritations) is: 'striving for mediocrity', used to describe those who could achieve so much, yet are content with their less than average achievements.
If we aren't improving, then we are realistically (ie relatively) going backwards.