Sitting is not uniquely harmful. Sitting still, in one shape, for three hours is the thing worth interrupting — and the interruption does not need to be a gym session.
The four
1. Chin tuck — 20 seconds
Sit tall. Draw your chin straight back, as if making a double chin, without tilting your head. Hold five seconds, release, repeat four times. This works against the forward head position a screen encourages.
2. Doorway chest opener — 30 seconds
Forearm flat against a door frame, elbow at shoulder height. Step through gently until you feel the chest open. Fifteen seconds each side. Counteracts a morning of reaching forward to a keyboard.
3. Seated thoracic rotation — 20 seconds
Feet planted, arms crossed over your chest. Rotate your upper back to one side as far as is comfortable, breathe out, come back. Five each way. The mid-back is where most desk stiffness accumulates.
4. Wrist extension — 20 seconds
Arm out straight, palm forward as if signalling stop, other hand gently drawing the fingers back. Ten seconds each side.
Why this beats a longer routine
Because you will actually do it. A ninety-second sequence that happens four times a day is worth considerably more than a twenty-minute routine you do twice and abandon. The frequency is the active ingredient.