Exercise amount for these dogs

Question
Hello, I was wondering how much exercise and what type should be given to these dogs and how offen:

Labrador retreiver adult

Jack russell terrier adult

Boston terrier 8 months

Answer
It is hard to lay out a schedule.  One of the things is that part of the exercise needs to be vigorous.  The 3 hour walk favored by some still never gives the dog the exercise it needs.  If you could turn the 3 of them loose in a fenced yard for a half hour or whenever they bark to come in, it would go a long ways toward giving them what they need.