Well it does take a few brain cells to realize that there's a dirt path next to the asphalt for practically the entire length of the Charles, for a good part of Fresh Pond, for a good stretch of the Minuteman Bikeway, for much of the emerald necklace, and that there are plenty of dirt or gravel trails in Arnold Arboretum, around Jamaica Pond, around the Brookline Reservoir and Franklin Park.
But I guess not everyone can cut it in Boston.
I think it's also reasonable not to consider Boston a college town. I lived there as a student and as a professional. Frankly, the city is a lot more geared towards its working population than its students. On the other hand, it's fair to say that much of the working population depends on the universities in some way (especially the hospitals)