When I'm on the road, doing my speaking gigs or just travelling to work with folk far away, I find things are a bit clearer.
Maybe it's view from 30000 ft, maybe the tiredness, maybe the isolation from the daily round but it always reminds me why I do what I do and why it matters. (props to Hugh)
And why not doing it is impossible (or at least not possible for me - check the middle 8 here for more details)