I've spent so much time teaching and being taught relaxations, visualisations and breathing exercises . . . mostly because they're all good ways to manage when mind and body seem determined to cause problems!
But not all exercises work for everyone; I can't create a safe space these days and yes, I know that's worrying.
In the meantime I fall back on an old favourite from an American physiotherapist I worked with, to make you concentrate on breathing. But no counting, nothing complicated. Just imagine a candle, several inches in front of you, the flame burning bright and straight. When you breathe in and out it will waver and flicker - so you try to breathe slowly enough not to blow it out.
It's not for everyone, but it works for me. Do you have a favourite exercise to still the mind and body?