This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:

Our primary objective is to assess the effects of self‐formulated conditional plans to change the health‐related behaviours of health consumers and healthcare professionals. Our secondary objective is to explore if the effects of self‐formulated conditional plans are modified by: (i) the form of the plan (e.g., implementation intention, action plan, coping plan); (ii) fidelity to plan development (did the individual participate in its development as planned?); and, (iii) complexity of the targeted behaviour (e.g., number of actions required; regularity of the behaviour).