If you find yourself on the northern half of the island and want some quiet road and rolling hill running, the St. Lucy area is a good option. There are numerous quiet, unnamed roads in the area between Highway 1B and Highway 1C. Create your own route through this rolling hill, green and pastoral terrain. These are narrow roads with no shoulder or sidewalk, but are not heavily trafficked. One good option is to park at St. Lucy Parish Church and run on the quiet side roads just north of it.
Note: These roads are open and exposed (i.e. no shade), away from the water, and no stores or facilities — so use caution in the heat.