Breath underlies all meditation practices. Breath also leads to shamatha, or peaceful abiding. This state of ease in concentration, of stability of meditative equipoise and altitude is part of the full body, whole person experience of shamatha. And, shamatha is the foundation for all further meditational experiences and states. Thus, it is the focus for all meditation practices until one has accomplished a stabilized state of shamatha repeatedly and with little effort.
Give this one a try!
(The quotes in the graphic are from the Yoga Sutras of Patanjali.)
Downloadable: Inter: a pranayama for shamatha