You say that you are too busy to meditate. Do you have time to breathe? Meditation is your breath. Why do you have time to breathe but not to meditate? Breathing is something vital to peoples lives. If you see that Dhamma practice is vital to your life, then you will feel that breathing and practising the Dhamma are equally important.
So sometimes things are ahead and sometimes they are behind; Sometimes breathing is hard, sometimes it comes easily; Sometimes there is strength and sometimes weakness; Sometimes one is up and sometimes down. Therefore the sage avoids extremes, excesses, and complacency.
I know I need to exercise. For some people, exercise is like breathing; for others, like me, it takes effort. Exercising is what I need for my metabolism and for a better sense of well-being.
Breathing is important in the practice of meditation because it is the faculty in us that is simultaneously voluntary and involuntary. You can feel that you are breathing, and equally you can feel that it is breathing you. So it is a sort of bridge between the voluntary world and the involuntary world — a place where they are one.