There is a stillness in the forest around Killiney Hill in south County Dublin. But when you pause, the quiet reveals itself to be layered: a dog barking in the distance, a bird calling, the soft crackle of wind through the trees. I’m watching Paul Reynolds — a high-performance business coach — close his eyes and settle into a practised calm, guided by a breathing technique he has refined over the years. Reynolds, formerly a renewable-energy consultant, spent nearly a decade as a partner at the Bristol-headquartered firm Everoze. When he joined the company, it was a team of just…