Exercise for12 wk black lab

Question
I have been trying to maximize exercise for my black lab puppy.  Some days
we have access to a huge field where we go to run, leashless, sometimes with
a friend's three year old doberman.  Great exercise and fun.  However, there
are many days I need to walk him on a leash on our country road to expend
the energy.  The outbound trip is a trial.  He pulls and is very distracted.  I
keep stopping to try to regain attentiveness, which works for about 10 feet.  
Then the pulling and distraction starts again. On the way back, it is awesome.  
He stays right where he is supposed to on my left side and we run.  It is fun.  
We come back, he is calmer - all things good.  The total route is a little less
than a mile. What can I do to improve the first half of the walk? Thanks

Answer
Stopping is a good technique, along with reversing direction.  Pulling the dog backwards works very well to.  The man that taught me the technique of stopping said ''If in an hour you don't make it out to the front walk, fine, you have thought him a lesson.''  Not all of us have that kind of patience and sometimes we need to get somewhere.  You may want to use a head collar.  Unlike a slip collar, you can use one at 12 weeks.  Just remember, no sudden snaps of the leash with ahead collar.  Read and follow directions.  

The leading brands are Promise, Haltie, and Gentle Leader. They have a strap going around the dogs nose looking something like a muzzle. They work by pulling the dogs head around. No other way gives you such great control with so little force. The prong collar is now a dangerous relic of value only for its macho looks. Do not consider using one without hands on instruction from somebody with plenty of experience with them.

One big difference between the average dog owner and top trainers is self discipline.  Better trainers get the results they get by forcing themselves to be patient and consistent.