On full moon and new moon days, it is of great benefit to take the eight Mahayana precepts at dawn and keep them for 24 hours.
In this way, negative karma is purified and positive karma develops through the mindfulness we bring to it.
We take the 8 Mahayana precepts with an attitude of great compassion.
Not only for our own benefit, but so that we may attain full awakening for the benefit of all living beings.
The 8 vows are:
Not killing, stealing, lying, no sexual activity, not making music, not adorning oneself, modesty and only having one major meal a day (lunch).
(Depending on serious medical issues tea, something very light for breakfast are allowed in exceptional cases).
As always: the motivation and seriosity counts!
The taking of the vows is accompanied by a ritual and recitations.
It is usually followed by:
Prostrations to the 35 Buddhas
https://www.lamayeshe.com/article/chapter/eight-mahayana-precepts-complete-practice
https://www.lamayeshe.com/article/chapter/appendix-3-confession-downfalls-thirty-five-buddhas