In beasts from large to small, there is an inverse mathematical relationship between base metabolic rate and life span. A fast heart equals a short life, a slow heart equals a long life. In fact, the total number of heartbeats in a lifetime is roughly constant between species.
This is likely part of the mechanism by which calorie restriction and intermittent fasting increase lifespan, the source of the saying “eat half as much, live twice as long”, and formalized in the Okinawan practice of “hara hachi bu“.
Another way to slow down is by relaxing. Hypnosis, meditation, guided visualization, brainwave entrainment, all provide at least the therapeutic effects of conscious relaxation.
And then, of course, there’s tai chi. With tai chi, you can practice relaxing actively, and slowing down quickly.