It is said that there are 90,000 "subtle gestures" to practice in Buddhism.
In Zen, every single thought we have, every single act we perform, every single statement we make, should be made such that we are mindful of the thought we are choosing to have, mindful of the act we are choosing to perform, mindful of the statement we are choosing to make. We've all had the experience of driving or walking along and suddenly realizing we have no idea where the last 20 minutes have gone. But less obvious are the daily chores you perform. Take showering, for instance. I know I can coast through my morning shower completely oblivious to everything. Sometimes it's too such a degree that I have no idea where the last 10 minutes went. But more often, I'm thinking about something else and yet am still somewhat conscious of the routine I'm following.
In true Zen practice, however, we are mindful of every single act. When my practice is strong, when I am washing my hair, I know with every ounce of my attention that I am washing my hair. When I am lathering the soap, I know with every ounce of my attention that I am lathering the soap.
The question is, why shouldn't I just enjoy letting my mind wander around while I shower? What's the point of joyfully enforcing such strong mindfulness? In Buddhism, the highest goal is to penetrate through our habitual delusion and see our true nature. How can we possibly attain this awakening if we cannot even maintain mindfulness on washing our hair? Mindfulness of all our actions IS our spiritual practice because when I am washing my hair, my true nature is "the washing of hair." When I drink tea, my true nature is "drinking tea." When I am dicing apples, my true nature is "the dicing of apples."
You might say, "Oh, I get that. I understand how that works." Or you might say, "That doesn't make any sense to me." It is my own personal experience that when I have been able to attain even the slightest glimpse of this truth (not intellectual knowledge or understanding, but true personal realization of this wisdom), the freedom, the joy, the clarity of mind I experienced was so great as to be indescribable. Mindfulness is the key to Awakening.
The 90,000 subtle gestures are the 90,000 different thoughts and actions you perform every day that give you the opportunity to think and act mindfully. Each of these 90,000 subtle gestures is a blessing, a stepping stone toward Awakening for the benefit of all beings.
EDIT (11/13/06): I just read a post over at The Journey that discusses mindfulness as discussed in Matthew 6:25-33. While we may disagree philosophically about the nature of the universe, the spiritual importance of mindfulness, living in the present, transcends such polarities.