Nurses will have Roscoe do "tummy time". For a limited amount of time they'll put him on his stomach instead of his back. This activity strengthens Roscoe's neck and back muscles. Also it engages his mind because he is able to see a different view of the world. If they put a mirror in front of him, then he's able to interact with his reflection.
On Saturday I came in and Roscoe had gotten sleepy after a few minutes of tummy time. The nurse left him sleeping and even left the mobile and music playing. Each mobile animal would circle down, land on his head, and then take off again. It was funny to watch, but she said that the motion probably gave him comfort since it felt like someone was stroking his head.