There are four sacred vows thought of as a pinnacle expression of one who intends to live as a Bodhisattva. Why to do that is another discussion.
The English translations of the four vows vary, however they're usually akin. Typically they're chanted three times in a dirge-like manner at the conclusion of traditional zen meditation periods, or other zen events, with bells and no whistles.
In Japanese: Shi Gu Sei Gan Mon
Shu Jo Muhen Sei Gan Do
Bon No Mujin Sei Gan Dan
Ho Mon Muryo Sei Gan Gaku
Butsu Do Mujo Sei Gan Jo
Here are some English renditions:
Creations are numberless, I vow to be one with them.
Delusions are inexhaustible, I vow to endure them.
Dharmas are boundless, I vow to be teachable.
The enlightened way is unsurpassable, I vow to embody it.
Zen Mountain Monastery
Sentient beings are numberless; I vow to save them.
Desires are inexhaustible; I vow to put an end to them.
The Dharmas are boundless; I vow to master them.
The Buddha Way is unattainable; I vow to attain it.
Zen Studies Society
However innumerable beings are, I vow to save them.
However inexhaustible desires are, I vow to extinguish them.
However immeasurable the Dharmas, I vow to master them.
However incomparable the Buddha-truth is, I vow to attain it.
Honolulu Diamond Sangha
The many beings are numberless; I vow to save them.
Greed, hatred, and ignorance rise endlessly; I vow to abandon them.
Dharma gates are countless; I vow to wake to them.
Buddha’s way is unsurpassed; I vow to embody it fully.
The above version was extracted form an short article you might find interesting here: Bodhisattva Vows.
If it's all too much, then focus on eliminating delusions!
The three marks of existence (sanboin) relate the basic yet quite profound qualities, or facts of lived experience. Those being:
1) Impermanence (change, mujō)
2) Craving (suffering, ku)
3) Non-Self (insubstantiality, kū)
Do you really expect something to be existing forever, ceaselessly unchanging, including your self? Are you aware of your habitual cravings and do they cause you grief?
If you can realize an understanding of the marks of existence, then it's said that you have attained nirvana. Ponder upon these marks, one at a time, slowly, turn them over in your being and see what awakens in you.