From Wikipedia: "Cult in this primary sense is literally the "care" (Latin cultus) owed to the god and the shrine."
I'm typing this about an hour before the actual Autumnal Equinox occurs. The coven I'm in will be holding our ritual tomorrow night. Me, I'm nearing the end of my pre-ritual rituals.
You see, while I can and do work magic or rituals or whatever is necessary at darn near a moments notice, I have found that both theurgy (magic/ritual aimed at spiritual growth/honoring the divine/etc) and thaumaturgy (magic/ritual aimed at material world miracles) work best with serious preparation.
It used to be the standard for magic users. Even now, I have friends who don't blink an eye at spending a full month or more preparing for a ritual. That month, depending on the ritual, might include celibacy (while married/living with significant other), dietary prohibitions, etc. Which of course is seen an VERY hardcore in modern America.
Me, I just like to spend the week before a high day working with the Patron Gods we're going to work with, on the seasonal changes whose energies we are working with, the magic we are trying to do. Often the 'working with' is working with a visualization for the week, whether it be an animal or a gold circle with a green dot in the center, on a black background, whatever.
Other friends of mine, on more ethnic pagan paths, do some more serious or long lasting cultus. One friend working with Apollo did a year without meat. Another does an assortment of fasts throughout the year.
The week before my first circle vigil in Ar nDraioch Fein - back at Samhain in about 1991 or 1992, I've packed my journals so can't check the date right now - I ate little meat, and only meat I killed myself. The day leading up to the vigil I only ate food I grew or at least harvested myself. I feel that preparation made a huge difference in the coherence of my mind, body, emotional, spirit, etc., for the vigil. It was pretty dang amazing!
Cultus. I recommend it.