TLDR: the Seinfeld "don't break the chain" approach, as described here:

http://lifehacker.com/281626/jerry-seinfelds-productivity-se...

much more detail, from my blog:

http://gilesbowkett.blogspot.com/2009/11/time-management-two...

http://gilesbowkett.blogspot.com/2012/08/my-gamified-life.ht...

http://gilesbowkett.blogspot.com/2010/02/calendar-win-rapid-...

good luck.