We were surprised last year when the Write three positive things about today habit doubled in participants in one day after Lifter Zack Shapiro blogged about it. The habit now has over 1,450 members: My @liftapp habit “Write three positive things about today” doubled in participants today. Got featured on @Lifehacker! http://t.co/glOg1oXy — Zack Shapiro (@ZackShapiro) January 15, 2013 What compelled…