The myth of 'just exercise more' — what actually moves depression numbers

Exercise has the strongest evidence base of any non-pharmacological intervention for mild-to-moderate depression. It also has the worst implementation record. The reason is simple — the advice is given without the dose, the pacing or the order. Here is what I actually tell my patients.

Three to five sessions per week, 30–45 minutes each, at moderate intensity (you can speak in short sentences but not sing). Aerobic preferred but mixed modality acceptable. Sustained for at least six weeks before judging the effect. Below this dose the antidepressant effect is unreliable; above it the marginal returns flatten quickly.

Do not start with the recommended dose. Depression flattens motivation; the recommended dose is unreachable from the bottom of the curve. Start with five minutes of walking outside, same time every day, for one week. Add five minutes per week. Patients who follow this ramp reach the clinical dose by week six and almost never quit. Patients who try to start at 30 minutes quit inside ten days.

Skip the gym membership in week one. Skip the smartwatch metrics. Skip the optimisation literature. The variable that predicts six-month adherence is none of the above — it is whether the activity has been bound to a specific time of day and a specific physical location, every day, no exceptions. Same minute, same door, same shoes.

If a six-week ramp completes and the PHQ-9 has not dropped by at least four points, exercise is doing its job but is no longer the rate-limiting factor. That is the moment to add structured Cognitive Regulation work, and where indicated, medication. Take the PHQ-9 on this site to baseline yourself before you start, and again at week six.