A.O.
C.,
I'm not sure if you are living in the Nashua area or closer to the coast. However, there are great running/walking trails at Mines Falls just behind Nashua South High School. There is plenty of parking in a couple of locations. Some of the trails are narrow and you have to cross a few roots but there are plenty of areas that are either paved or wide and flat enough for an alterain stroller. I hope this help.
A.