Exact interpretations vary, but it seems that the initial steps are usually interpreted as a progression of setting up mindfulness, settling the mind on the breath, calming the breath and body, and so on.
This step, "releasing the mind", is generally interpreted to be referring to Jhana:
[12] He trains himself, 'I will breathe in releasing the mind.' He trains himself, 'I will breathe out releasing the mind.'
Footnote: AN 9.34 shows how the mind, step by step, is temporarily released from burdensome mental states of greater and greater refinement as it advances through the stages of jhana.
I've seen the jhana factors arise a couple of times in my practice (particularly piti and sukkha and more specifically "showering rapture / bliss / piti"). At the time they arose I refrained from pursuing, acquiring, or obtaining anything, except for mindfulness while focused on the in and out of the breath. My resolve was not where was I going or wanting to arrive, but more of an attitude of already having arrived. I cheerfully sat alone in my apartment with no expectations. In fact, I was not aware of jhana at the time and in my recent studies of jhana did I relate with what I read.
Please let me be clear: I am not speaking as though I have perfected or attained jhana. Perhaps it was "wrong jhana factors" or "right jhana factors", I don't know, but what I do know is the bliss / joy and happiness that is there far exceeds anything I've ever known. They did not come as a result of anything, they were just there... if that makes any sense.
In the end, I tend to encourage anyone meditating to remain focused on the breath, be mindful, be objective, and let come what may. I do not fret: how long and where I am going. I simply watch my thoughts, body, and primarily the breath as they arise. I watch the breath at the tip of my nose. Realize that atman and this existence is nothing, in which is not a destination, state, conceptualized notion, so it won't come by desire or ambition. Just sit and watch your conditioned thoughts arise, "note", disappear, and breathe.
Ironically I tend to believe jhana arises in the "effort" of nothing, "striving" (a contradictory and poor word) of letting the mind settle / still.
I feel as though I am deficient in my explanation, but glean what you can if you wish.
