Sit
No instructions, no reading. Pick a length and go. Campbell’s own position is that the doorway hardly matters — a mantra, the breath, an imagined soccer ball all do the same job of pushing extraneous thoughts out of the way.
Keep this tab open. The screen will stay awake and dim itself — your phone can lie face down. On iPhone, sound stops if you lock the screen or switch apps, which is a limitation of the browser rather than a setting you can change.