A sad way of not praying the Rosary is to leave it for the end of the day. If you say it when going to bed, it will be done at best badly and with no meditation on the mysteries. It will be difficult then to avoid routine, which is what drowns true piety, the only piety worth the name.
The Rosary is said not with the lips alone, muttering Hail Marys one after the other. That is the way over-pious old men and women rattle them off. —For a Christian, vocal prayer must spring from the heart, so that while the Rosary is said, the mind can enter into contemplation of each one of the mysteries.
You always leave the Rosary for later, and you end up not saying it at all because you are sleepy. —If there is no other time, say it in the street without letting anybody notice it. It will, moreover, help you to have presence of God.