Breathing slowly and deliberately during a massage can help the body relax more fully, since shallow breathing tends to keep the nervous system in a low-level alert state. A simple technique is to inhale for a count of four, hold briefly, and exhale for a count of six — the longer exhale in particular signals the body to relax.
You don’t need to maintain perfect rhythm throughout the whole session; even a few minutes of focused breathing at the start can set the tone for the rest of the treatment.