Instead, Hadfield uses these anecdotes of getting to and being in space as a way of sharing his insight on how to live life on Earth. Far from being clichéd "it's the journey, not the destination" exposition, he gives pretty solid advice on attitude, most of which runs counter to the overly-positive aphorisms you generally see.
I have a totally mixed feelings regarding the relentless-positive philosophy prevalent in some self-help circles. I think that the overly-positive stuff was an over-reaction to overly-negative views held before (when children and adults were told they not worthy to change their lot in life, etc). The hardest thing (and possibly wisest thing ever) is to conceive of the zero ...zero, which was invented late even in math. Zero as the middle of a scale ranging from negative to positive is a special point of balance (someone who's reading the book please chime in here!) Phil Plait quotes Hadfield's advice to find the balance point:
Another bit I liked was, "aim to be a zero".