Sunny Consolvo Predrag V. Klasnja David W. McDonald James A. Landay Goal-setting considerations for persuasive technologies that encourage physical activity. 8 2009 PERSUASIVE http://doi.acm.org/10.1145/1541948.1541960 conf/persuasive/2009 db/conf/persuasive/persuasive2009.html#ConsolvoKML09