In Kadampa Meditation Center LA’s words
The practice of taking and keeping the eight Mahayana precepts is a special practice of moral discipline that is performed with bodhichitta, the compassionate wish to attain enlightenment for the benefit of all beings. The essence of this practice is taking eight precepts and keeping them purely for twenty-four hours. We first need to receive these precepts from a qualified Preceptor, and then we can take them on our own as often as we wish. Instructions on both these methods are included in this prayer booklet. Because this practice is motivated by bodhichitta it is especially powerful for purifying negativities, accumulating merit—a positive strength of mind—and creating the cause for us to attain the unsurpassed happiness of enlightenment. This booklet contains a brief explanation of the practice of keeping the eight Mahayana precepts.