There is an old yoga myth about how yogis breathe:
Yogis used to believe we each had a certain amount of breaths in our lifetime. Somehow we were born with a pre-allotted number of inhales and exhales. Through yoga practice the yogis lengthened out their breaths, creating longer, fuller, more complete lives.
We might not subscribe to this idea any more, but the intention is the same: By being more consciously aware of each breath we become active participants in our own lives, living more fully.
Can you be so aware of tracing each inhale and exhale? Can you be so intimately involved with each breath that every moment seems a little longer? What would be different if you only had so many breaths in your life quota?