Running with my 8 month old chocolate lab

Question
I would like to include my dog on my runs, but not sure how far to run with her
or how to increase her mileage.  I would only take her on 3-4 mile runs,
combination of street/trails.  She's always eager and a great partner, but I don't
want to push her puppy bones too fast.

Answer
I am afraid it would be better to put off until next summer.  At 8 months their joints are still developing and sustained high impact activity such as running, could damage them.

Keep her lean, see http://www.longliveyourdog.com/twoplus/RateYourDog.aspx  Switching to an adult chow for the larger breeds early, slows growth and helps develop sturdier joints.  If you are still feeding a puppy chow, make your next bag the adult version of the same thing and work it in until after a week you are feeding all adult chow.