Find something with nothing in it to look at: sky, a blank wall, a ceiling, a stretch of grass. Do not concentrate on it. Let your attention spread out over it.

What the research says

A randomised controlled trial found that self-guided physical activity, mindfulness meditation and heart rate variability biofeedback all reduced stress and improved wellbeing to a similar degree, which suggests the choice between routes can follow preference. Open gazing was not one of the arms, so it has not been shown to work in its own right. Use that finding as permission to pick what suits you rather than as evidence for this one.

Strength of evidence: one line of research. A single study, or a theoretical account.