Two years ago I joined CANCER RESEARCH UK'S DRYATHLON (dryathlon.org.uk).  In 2015, I'm doing it again, pledging not to touch a drop of alcohol from 9am on 1st January 2015 to 9am on 1st February 2015. But, I'm not asking anyone to sponsor me, rather NOT buy me a drink and donate the money instead. Two years ago, this was why I was doing Dryathlon, and its pretty much the same again this year: 

http://profmikeweed.wordpress.com/2013/01/04/why-physical-activity-promotion-policy-isnt-helping-the-fight-against-cancer-or-why-im-joining-cancer-research-uks-dryathlon/