Sedentary behaviour during adolescence is associated with an increased risk of depressive symptoms at the age of 18, a UK study has found. Healthcare practitioners should ensure that parents and carers are aware of government advice on how much physical activity children and young people should be doing (i.e. at least 60 minutes of moderate-vigorous activity per day). Adolescents should be routinely asked about physical activity and sedentary behaviour levels, and every opportunity taken to emphasise the mental health benefits of physical activity.