When you see breath energy in a constant way, it’s a lot easier to adjust the breath in a way that feels right, feels healthy, feels nourishing. You can gain a sense of fullness without feeling stuffed.
"Before you take up the three perceptions of inconstancy, stress and not-self, [the Buddha] has you develop other perceptions first — in particular the perceptions that lead the mind to concentration. While you’re here practicing concentration, focus in on your breath. What keeps you with the breath? A perception, a mental label that says “breath.” And a lot of the concentration practice is learning how to gain a perception of breath that you can hold in mind for long periods of time with a sense of ease, a sense of well-being. You test different perceptions of the breath to see which ones hold — in other words, which ones you can stick with. This would seem to go against the perception of inconstancy, and it does. You’re actually looking for a perception you can hold onto as constant. You want to see the breath as something consistent and pleasant you can stay with. For example, if you see the in-breath and the out-breath as two radically different things, it’s going to be hard t...