I use Caroline Marois, a professional dog walker to take my dog out for group walks once a week or so. She is absolutely amazing - my dog loves her, she's super reliable (came last friday in the snowstorm) and she picks up/drops off the dogs. Private walks are at least one hour and group walks usually have your dog away from the house for 4 hours (incl travelling). My dog comes home tired, mentally and physically, and incredibly happy. Her website is
http://www.petalamode.com/
I can't recommend her enough!