First of all, it is contemplative prayer - an ancient type that pre-dates protestantism/bible Christianity by many centuries. It is a very profound, multi-layered prayer in which the Holy Spirit will reveal insights to you as you contemplate. It brings peace to your spirit, but far better, you can offer it for any intention that you believe is in accord with God’s will. Amazing things can and will happen.
It is not a magic prayer - the “Hail, Mary” prayers are certainly a prayer by themselves, but they are also background music, if you will, setting a cadence to accompany your contemplation. Should you ever begin to pray the Rosary, visual stimulation or (name removed by moderator)ut to accompany your prayer and meditation may help assist you.
Consider reading the appropriate sections from the Gospels that accompany each mystery as you pray. You will notice things in those passages that you never saw before. Even the most familiar passages will take on a new, more profound meaning. There are YouTube videos and websites on the web which offer collections of sacred art pertaining to each mystery. You can contemplate what is being depicted by the artist as you pray.
Under Her Starry Mantle is one such site. Scroll down the home page and click on the art collections along the right border - they will open to larger, even full screen images.
Come Pray the Rosary is another site in which you can watch video of the holy land as you contemplate.
It is NOT NOT NOT “vain” repetition. There is nothing vain about contemplating the life of Christ! Vain means empty. Contemplating the life of Christ can never be empty. It fills you! It has eternal meaning and provides eternal benefit. It is not a requirement, but will become one once you pray it.
A warning: You will become addicted to it, as it draws you into a more intimate relationship with Father, Son, Holy Spirit, and your mother in heaven.
- From someone who did not pray a Rosary for years after becoming Catholic.