If you’ve ever tried to start exercising—and then stopped after a few weeks—you’re not alone. Nearly everyone wants to be more active, but turning good intentions into long‑term behaviour is one of the biggest challenges in health and fitness. 

The good news? Scientists have spent decades studying how and why people change, and their research has produced several reliable frameworks that can help us understand our habits and shape new ones. In this blog, we break down popular, evidence‑based behaviour‑change models so you can use them to build exercise habits that actually stick. 

1. The Transtheoretical Model (Stages of Change): Understanding Where You Are 

One of the most widely used frameworks in health psychology is the Transtheoretical Model (TTM). It proposes that behaviour change isn’t a single event—it’s a process with stages: 

1. Precontemplation – not thinking about exercise at all 

2. Contemplation – considering becoming active 

3. Preparation – planning or starting small efforts 

4. Action – exercising regularly (under 6 months) 

5. Maintenance – sustaining exercise long term 

Why does this matter for you? Because each stage requires a different strategy. 

• If you’re in contemplation, learning the benefits of exercise or talking to others may help. 

• If you’re in preparation, setting realistic goals or planning workout times is key. 

• If you’re in action, building routines and tracking progress supports consistency. 

Research shows TTM‑based interventions can effectively improve physical‑activity adoption because they match support to the person’s current readiness to change (Prochaska & Velicer, 1997; Marshall & Biddle, 2001). 

2. Social Cognitive Theory: The Power of Confidence and Environment 

Ever feel more motivated when a friend joins you for a workout? Or when you see someone you identify with achieving a fitness goal? These experiences fit within Social Cognitive Theory (SCT), developed by psychologist Albert Bandura. 

SCT states that behaviour is shaped through three interacting forces: 

1. Personal factors 

Your motivation, beliefs, feelings. 

2. Behaviour 

What you do and the feedback you receive. 

3. Environment 

Your social support, community, physical surroundings. 

One of the most important concepts in SCT is self‑efficacy—your belief in your ability to succeed. 

Research consistently shows that people with higher exercise self‑efficacy are more likely to start and maintain activity (Bandura, 2004; McAuley & Blissmer, 2000). 

How to apply SCT for exercise: 

• Set small, achievable goals to build confidence 

• Model success by following people with similar backgrounds or circumstances 

• Shape your environment—join a class, find a partner, or keep your workout gear visible 

Small wins create momentum, which builds confidence, which fuels more wins. 

3. Self‑Determination Theory: Why Motivation Quality Matters More Than Amount 

We often talk about having “more motivation,” but Self‑Determination Theory (SDT) shows that the type of motivation matters more than the quantity. 

SDT describes two kinds: 

• Extrinsic motivation: exercising for external reasons 
  (e.g., weight loss, doctor’s advice, rewards) 

• Intrinsic motivation: exercising because it feels good 
  (e.g., enjoyment, satisfaction, stress relief) 

People are far more likely to stick with exercise when their motivation becomes intrinsic. SDT says we can strengthen intrinsic motivation by fulfilling three basic psychological needs: 

1. Autonomy: “I choose to do this.” 

Choose activities you enjoy. 

2. Competence: “I can do this.” 

Start at the right level and track progress. 

3. Relatedness: “I feel connected.” 

Join a group, class, or online community. 

Studies show that meeting these needs improves both exercise adherence and enjoyment (Deci & Ryan, 2000; Teixeira et al., 2012). 

4. The COM‑B Model: A Simple Formula for Changing Any Health Behaviour 

A more recent and practical model is COM‑B, which states that a behaviour occurs when three things come together: 

C – Capability 

You must have the physical and psychological ability to exercise. 
Examples: knowledge, skills, fitness levels. 

O – Opportunity 

Your environment must support the behaviour. 
Examples: time, access to facilities, social support. 

M – Motivation 

Your thoughts and feelings must encourage rather than block action. 

If any one of the three is missing, the behaviour won’t happen. 

For example: 

• Someone may have motivation but lack opportunity (e.g., no childcare). 

• Another person may have opportunity but lack capability (e.g., unsure how to train safely). 

COM‑B helps by identifying which component is the biggest barrier—and then designing the right intervention. 

In physical‑activity research, COM‑B has been shown to help improve exercise participation by providing a clear structure for identifying individual barriers and creating tailored solutions (Michie et al., 2011; Barker et al., 2016). 

5. Habit Formation Theory: Making Exercise Automatic 

While motivation gets you started, habits keep you going—especially on days when motivation is low. 

Habit formation involves repetition in a stable context, using the cue–routine–reward structure: 

1. Cue – a trigger (e.g., your alarm or putting on your trainers) 

2. Routine – the behaviour (your workout) 

3. Reward – the positive outcome (energy, satisfaction, tracking your progress) 

Research shows that simple, consistent behaviours can become automatic in as little as 8–12 weeks, though it varies by person and complexity (Lally et al., 2010). 

How to build an exercise habit: 

• Link exercise to an existing routine (e.g., after school run, lunch break). 

• Keep workouts short and simple at first. 

• Celebrate finishing—record it, acknowledge it, or treat yourself to a non‑food reward. 

The more automatic it becomes, the less mental effort is required to keep going. 

Pulling It All Together 

Each behaviour‑change model highlights something unique: 

• TTM helps you understand your stage and choose appropriate strategies. 

• SCT empowers you with confidence, role models, and a supportive environment. 

• SDT improves long‑term adherence by building intrinsic motivation. 

• COM‑B helps identify capability, opportunity, and motivation barriers. 

• Habit theory turns repeated actions into automatic routines. 

You don’t have to use just one model—many people combine elements from each. Start small, build confidence, support yourself socially, and choose activities you genuinely enjoy. With the right approach, exercise becomes not a chore but a natural part of life. 

Peer‑Reviewed References 

1. Bandura, A. (2004). Health promotion by social cognitive means. Health Education & Behavior, 31(2), 143–164. 

2. Deci, E. L., & Ryan, R. M. (2000). The “what” and “why” of goal pursuits: Human needs and the self-determination of behavior. Psychological Inquiry, 11(4), 227–268. 

3. Lally, P., van Jaarsveld, C. H., Potts, H. W., & Wardle, J. (2010). How are habits formed: Modelling habit formation in the real world. European Journal of Social Psychology, 40(6), 998–1009. 

4. Marshall, S. J., & Biddle, S. J. (2001). The Transtheoretical Model of behavior change: A meta-analysis of applications to physical activity and exercise. Annals of Behavioral Medicine, 23(4), 229–246. 

5. Michie, S., van Stralen, M. M., & West, R. (2011). The behaviour change wheel: A new method for characterising and designing behaviour change interventions. Implementation Science, 6, 42.