Here is the guy that says you need to try new things for 30 days to make an impact:
Matt Cutts: Try something new for 30 days
Find his 30-day challenges here: http://www.mattcutts.com/blog/type/30-days/
Find my current status here: http://runkeeper.com/user/guidooswald/profile (add 1 day that is was not tracked with RunKeeper)
