Prana is the life energy - yama is traditionally referred to as a restraint of the breath. Various techniques are offered within the yoga traditions for methods of controlling or regulation of the breath. Practicing these techniques, it is advisable to follow the advice of your yoga teacher, or one who is acquainted with the effects of these techniques. (I know you are, Rumi!)
The breath can be regulated by duration of inhale or exhale, location of breath, or by how number. There is a natural occurrence of a cessation of the breath, in which the ingoing and outgoing breath, merge as it were, in their dance together. This is observable at the turning of each breath, and one can become aware of it even when not doing a formal pranayama practice. A more advanced practice is that of extending the pause, although as Rumi comments, it is an effortless effort.
Investigating the pause between the incoming and outgoing breath, the point of stillness, is a lovely offering of the mind's attention to the dance of prana.