The menstrual cycle works by releasing eggs, getting them ready for fertilization, and then disposing of the egg if not fetilized. Most cycles are roughly 28 days long. Your hormones get your body ready for ovulation, the release of the egg, at around day 14. Your hormones then work to prepare the egg to be fertilized. If the egg does not, the body will dispose of the egg and your perios will begin, flushing the egg from your body.