If You Build It, They Won't Walk
Researchers at the University of California, Santa Barbara found that the building a new trail in an area didn't result in an increase in physical activity.
"One unique aspect of the study was its "before-and-after" approach - it measured the neighbors' walking-jogging-cycling frequency before the trail was built and after it was completed. About 87 percent of those who used the new trail reported they were pursuing these activities before the path was constructed and used sidewalks or more distant trails. Proximity to the trail had no significant effect on total physical activity; those near it were no more likely to use it than those farther away."