A week is the perfect measure of time.
A week is the most useful division of time. It is long enough to begin measuring contributions towards progress.
A week is 2% of the year. 2% is the perfect amount of potential in relation to a year - it is palpable.
Imagine for this week, you go the gym or play a sport, save or plan towards your financial freedom with a business, are available to friends and to family, you will have a +2% yield toward the year (towards life!), all within one week!
I first read this phrasing ("A week is 2% of the year") at http://nat.org/.