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Why Psychology Matters in Health and Fitness

You might assume that health and fitness is all about what we eat and how we move. And of course these things matter. But what’s arguably even more important is WHY we eat and move (and drink, work, sleep, rest and play) in the ways we do. And that’s where psychology comes in - the scientific study of the mind and behaviour. If we don’t consider psychological factors when trying to understand people’s health behaviours then we’re missing the point. Humans are not robots. We are flawed, messy and complicated, and do not behave in textbook ways.

Let’s consider the example of a fictional client; we’ll call her Ruby. Ruby is a 42 year-old single mum and supermarket store manager. Ruby often finds herself stressed because she works long hours and has two lively children, plus an elderly mother who’s spent the past year in and out of hospital. When Ruby’s not working or caring for her loved ones she likes to unwind with a bottle of wine and a takeaway with her girlfriends. She’s not exercised in 25 years because she hated P.E. at school and never got picked for the teams. Recently however, Ruby found out that she is prediabetic and her doctor has told her to improve her diet and increase her activity levels before her health deteriorates. This is what brought Ruby to me, and she has asked for my help with establishing an exercise routine.

After chatting with Ruby for just twenty minutes, I already have a good idea of how adherent she might be to a healthier lifestyle, and what she will need from me for the best chance of success.

I know that Ruby has high stress levels, which may affect her health behaviours. Stress can influence our appetite and food choices; research suggests our appetites often increase when we’re stressed, and we’re more likely to eat sweet and convenience foods (Kadnihah et al., 2006). It will be important to frame exercise as a tool to help Ruby manage her stress, rather than it being seen as another stressor in her life. I will suggest that Ruby attempts short, frequent workouts to suit her busy lifestyle and help control her stress throughout the week. This might also mean Ruby is less inclined to use junk food as a coping mechanism for her stress.

I get the impression that Ruby is a conscientious person, as her commitment to her work and family shows that she works hard for things she cares about. This bodes well for sticking to an exercise routine, as research suggests that the personality trait of conscientiousness is positively associated with exercise adherence (Rhodes & Smith, 2006).

I know that Ruby has low exercise self-efficacy, which means she lacks belief in her ability to exercise. This is probably a result of her negative childhood experiences of P.E. Exercise self-efficacy is a strong predictor of exercise adherence - one study found that adults with high exercise self-efficacy were more likely to be active five years later than those with low exercise self-efficacy (McAuley et al., 2007). It will therefore be important to help Ruby find ways of exercising that make her feel competent. I will encourage her to explore different types of exercise in and out of the gym, so that she discovers something she feels able to do and her exercise self-efficacy increases.

I’m aware that Ruby is extrinsically motivated to exercise, which means she is motivated by an external outcome. In this case the outcome is her health, because she wants to avoid getting diabetes. It’s critical to understand somebody’s ‘why’ when it comes to exercise, because it can help them to stick at it during challenging times. Many new exercisers like Ruby are extrinsically motivated, whereas often those who have exercised for longer become intrinsically motivated, which means they are motivated by internal factors such as feeling good or enjoyment (although some beginners may also be intrinsically motivated). Ruby might not always be extrinsically motivated, but what’s important now is to identify that she is and use this to support her.

I know that Ruby is preparing to make a behaviour change, because she has contacted me and intends to purchase personal training. Psychologists would describe this as being in the ‘preparation’ stage of change (Prochaska et al., 1994). It is important to know how ready somebody is to change, because if they are not even contemplating making a behaviour change, it will be almost impossible for the best coach in the world to help them change their ways. If on the other hand somebody does want to make a change, like Ruby, they will be far more receptive to interventions like personal training, as they already have that psychological ‘buy-in’. It’s now my job to help her make exercise a habit.

As you can see, I’ve already learnt a lot about Ruby and have several ideas about how I can support her. And it doesn’t stop there - once we start working together I will learn more about Ruby’s self-esteem, learning style, attention, memory, attitudes and values, amongst other psychological factors that will affect her health behaviours.

So the next time you find yourself thinking that improving health is a simple equation of more vegetables and more exercise, remember that whilst that’s theoretically correct (to some extent, because there are so many more things that affect health beyond diet and exercise), it’s not particularly helpful. What’s far more useful is to ask questions about somebody’s mental health, personality, self-efficacy, motivation, readiness to change and the other things I’ve mentioned above. If you’re a health or fitness professional, these answers will help you to tailor your interventions to the human in front of you. And if you’re somebody working with a health or fitness professional, you will be heard and supported. And being heard and supported makes behaviour change far easier than going it alone.


Kandiah, J., Yake, M., Jones, J., & Meyer, M. (2006). Stress influences appetite and comfort food preferences in college women. Nutrition Research, 26, 118-123. 10.1016/j.nutres.2005.11.010.

McAuley, E., Morris, K.S., Motl, R.W., Hu, L., Konopack, J.F., & Elavsky, S. (2007). Long-term follow-up of physical activity behavior in older adults. Health Psychology, 26, 375–380.

Prochaska, J. O., DiClemente, C. C., & Norcross, J. C. (1994). Changing for good. New York: Avon Books.

Rhodes, R. E., & Smith, N. E. (2006). Personality correlates of physical activity: A review and meta-analysis. British Journal of Sports Medicine, 40, 958-965.


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