Try a Guided Meditation
From Pat Coffey of the Charlottesville Insight Meditation community, this post shares a guided “body awareness” meditation that I think you’ll like. A meditation practice is part of self-care for ADHD because it is calming, centering, and builds awareness and tolerance.
When you notice your thoughts wandering, gently welcome your awareness back - no problem.
For more information about the benefits of meditation on your brain, a good source is from the NIH library: Impact of meditation training on the default mode network during a restful state https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3541485/