Ed Deci and Richard Ryan introduced SDT in 1985 as a framework for understanding motivation and how it can enrich our lives, formalizing it in 2000. Since then, many health interventions have been created with SDT at their core. In their 2012 paper Fortier, Duda, Guerin, and Teixeira, all of whom have intervention studies to their credit, review the landscape of SDT-based intervention studies for promoting physical activity and go in-depth on three new randomized-control trials. For those interested in the real gems that have come out of SDT intervention studies such as how to promote autonomy support as well as how to promote structure while still making clients feel empowered, this is a great place to start learning about the current research. The study is also available free online, which is a price you can’t beat.

Fortier, M. S., Duda, J. L., Guerin, E., & Teixeira, P. J. (2012). Promoting physical activity: development and testing of self-determination theory-based interventions. International Journal of Behavioral Nutrition and Physical Activity, 9(1), 20. doi:10.1186/1479-5868-9-20


Habit-formation has gotten hot recently with books like Chip and Dan Heath’s Switch, Charles Duhigg’s The Power of Habit, Martin Grunburg’s The Habit Factor, and Leo Babauta’s Zen Habits. The recipe for habit-formation is really quite simple, but paraphrasing Dan John. “never easy.” To see just how not easy, check out Gardner, Lally, and Wardle’s (2012) “Making health habitual.” These three researchers from the University College London are at the forefront of Health Habit research and this free paper represents the cutting edge of advice to practitioners. Included in this review is a reference to Lally (2010) which found that habit formation in the real world does not take 21 days, as mythology has reported. Rather it takes an average of 66 days with a range of 18-254 days. That’s a big difference, and we would all be serving our clients better if we began managing that expectation.

Gardner, B., Lally, P., & Wardle, J. (2012). Making health habitual: the psychology of “habit-formation” and general practice. The British Journal of General Practice: The Journal of the Royal College of General Practitioners, 62(605), 664–666. doi:10.3399/bjgp12X659466
Lally, P., van Jaarsveld, C. H. M., Potts, H. W. W., & Wardle, J. (2010). How are habits formed: Modelling habit formation in the real world. European Journal of Social Psychology, 40(6), 998–1009. doi:10.1002/ejsp.674


Coaches, bosses, spouses, accountants, late night TV… There is no shortage of people telling our clients that they lack discipline. However, research since 1998 has shown fairly definitively that willpower is not fixed. Discipline might be more limited, and trainable, than we think. The social scientists studying “Ego-Depletion” have made impressive breakthroughs in what has become “The Strength Model of Willpower,” well reviewed by Hagger, et al. (2010). The Strength Model has linked willpower to perceived changes in blood glucose freely available to the brain. Essentially, making ourselves do something (like a desired new habit) or resist something (like an undesired old habit) costs blood glucose. The more we tax the system, the more sensitive we become to failures of will. The implications for habit-change, coaching, and even programming athletes is undeniable and far-reaching. This review of the research so far is a great place to start an academic review of how limited willpower effects our clients’ lives, but for a more lay approach check out this month’s Recommended Reading.