Practice is what one does in response to one's understanding of life. Practice will consequently change as one's understanding changes; life itself is a process of change. Practice may include mindfulness and meditation, or more commonly simply living one's life fully and completely, based on sound principles. The principles should respond to life as Buddha's eight-fold path responds to his Noble Truths. They should also respond to the reality of the present moment and present situation, including one's thoughts and emotions as well as one's relationships, ultimately to all beings. For me personally, my many problems and failures warrant my practice, that ideally includes continuous mindfulness, as well as daily Zazen, usually during sunrise and sunset, and seasonal intensive retreats.

It takes a book, if not one's life, to understand Practice. Stephan Batchelor, in his book "Buddhism without Beliefs" characterizes Buddhist Practice as what Buddhists do with respect to Buddhist principles. Thich Naht Hahn's small book "Be Still and Know" includes "Peace is all around us, in the world and in nature, in our bodies and our spirits. Once we learn to touch this peace, we will be healed and transformed. It is not a matter of faith; it is a matter of practice." From the book "Beyond Thinking" by Dogen as edited by Kazuaki Tanahashi, "spiritual practice is not some kind of striving to produce enlightenment, but an expression of the enlightenment already inherent in all things."

Kosho Uchiyama's "Opening the Hand of Thought" best describes practices I believe are warranted. In his concluding chapter, that is an edited version of his final talk when retiring after over thirty as a monk and ten years as abbot of a Japanese temple, Uchiyama strongly advocates and discusses seven points of practice:

1. Practice to contribute to Buddhadharma (i.e., practice for the benefit of truth)
   
2. Zazen itself is Our Truest and Most Venerable Teacher
   
3. Zazen must work concretely in our lives (helping to develop our practice)
   
4. Live by vow (particularly the four Bodhisattva vows) and root it deeply
   
5. Endeavor to Practice and Develop (magnanimity, compassion, dedication, generousity)
   
6. Sit Silently for Ten Years, (and then another ten, and ....)
   
7. Cooperate with One Another (supporting practice, and places of practice)

Uchiyama's teacher, Kodo Sawaki Roshi, was also my Zen teacher's teacher; that is Kobun Otogawa's teacher. Perhaps a key point in Uchiyama's book, in Sawaki's words, is that "Zazen is the self doing itself by itself ... the (universal) self selfing the self". Self is ubiquitous in Uchiyama's expression of Zazen, that returns Zen to its roots as our flesh and bones practice, rather than our intellectual understanding. Self becomes increasingly evident as one's practice "opens the hand of thought". From some translations of the precepts, "Self-nature, while inconceivably wondrous, mysterious, and profound, is ungraspable and imperceptible."

From my years of experience during sesshins led by Kobun Roshi, I am confident that Kobun's teachings are expressed by Uchiyama's seven points of practice, even though Kobun did not express them in that way. Uchiyama's practice, like Kobun's practice, leads one toward a magnanimous and compassionate heart, and an open, reflective and responsive mind.

Kosho Uchiyama, as briefly described in Wikipedia.
Kobun's Teachings (exemplified) are on Jikoji's web site.
Kobun Chino Otogawa Roshi describes Kobun.
Kobun's Discussions is a series of his earliest discussions, from 1973.
Mind and Meditation