There is no doubt about the benefits of exercise. Physical activity is associated with a reduced risk of coronary heart disease, obesity, type 2 diabetes, and other chronic diseases and conditions.1 Despite the wealth of information about the benefits of exercise, sedentary adults often find it hard to change their behaviour in a sustainable manner. The development of interventions that support behaviour change is therefore of general interest. Social cognitive theory,2 which explains why people behave as they do, has been used to develop strategies that support changes in behaviour. Examples of such strategies include encouraging people to choose from several options, goal setting, and encouraging clients to monitor their progress through record keeping. In a linked paper (doi:10.1136/bmj.f576), van Nimwegen and colleagues use such strategies to encourage a long term increase in participation in activity among patients with Parkinson’s disease.3

It is more important and more difficult for patients with Parkinson’s disease (and other long term neurological conditions) to increase exercise levels than it is for healthy adults. More important because, in addition to the cardiovascular benefit, exercise may have a positive effect on the non-motor symptoms of Parkinson’s disease, such as fatigue, insomnia, depression, and constipation. In addition, it may …