From Wikipedia:
The Rosary (from Latin rosarium, meaning “rose garden” or “garland of roses“ is a popular and traditional Roman Catholic devotion. The term denotes both a set of prayer beads and the devotional prayer itself, which combines vocal (or silent) prayer and meditation. The prayers consist of repeated sequences of the Lord’s Prayer followed by ten prayings of the Hail Mary and a single praying of “Glory Be to the Father”; each of these sequences is known as a decade. The praying of each decade is accompanied by meditation on one of the Mysteries of the Rosary, which are events in the lives of Jesus Christ and his mother, the Blessed Virgin Mary.
Daily prayers and meditations are surely a good thing. And Jesus gave us the Lord’s Prayer in response to a request from the disciples to teach them to pray. So anything that helps with daily prayer sounds like a good thing. But the devil is in the details (again from Wikipedia):
The rosary is part of the Catholic veneration of Mary, which has been promoted by numerous popes, especially Leo XIII, known as “The Rosary Pope”, who issued twelve encyclicals and five apostolic letters on the rosary and added the invocation Queen of the most Holy Rosary to the Litany of Loreto.
The Bible describes Mary as a woman — blessed, for sure — but just another human like all the rest of us, now dead and buried. Veneration of Mary, prayers, supplications, etc., — these are not based on the Bible but on the huge body of (catholic) church liturgy.
And simply repeating some one else’s chosen words until it becomes a monotonous dirge — where’s the scriptural support in that? If you want to do a rosary, well and good, especially if it brings you closer to Jesus; but pick a your own set of scriptures, and change them every so often.
The Bible suggests a number of things should be done daily. But they’re all much more practical and outwards focused than the rosary. Two examples:
“If anyone would come after me, he must deny himself and take up his cross daily and follow me.” (Luke 9:23)
“Make it your ambition to lead a quiet life, to mind your own business and to work with your hands, just as we told you, so that your daily life may win the respect of outsiders and so that you will not be dependent on anybody.” (1 Thess 4:11-12)