I use Insight Timer app, just the timer function, and do box breathing.

1. Breathing in for the count of 4

2. Hold for the count of 4

3. Breathing out for the count of 4

4. Hold for the count of 4

(I listen to an analogue tick tock clock for rhythm).

As thoughts come up, with kindness to yourself, bring your attention back to counting

Box breathing has been my go-to mindfulness technique- give it a go!