My Labrador pup wont walk on the leash.

Question
I have a Black Labrador Pup, he's just over 3 months old, has had his second lot of vaccinations. In the house he is very playful but when it comes to walking him he resists, it starts from when i try putting the harness on he just runs away or whimpers. when walking he just sits down and refuses to walk, i wait it out with him and when he finally does walk i reward with a treat but straight after he sits down and refuses again. I have tried him off lead, when i remove the lead he just sits down next to me, if i run off he will run after me and if i walk he finally does follow (probably scared I'm going to leave him but will not run around of his own accord, even i throw a ball or toy. The only time he seems happy when he is out is if he sees another dog or person, then he goes manic, jumping all over the person he sees and playing with the dogs he meet (obviously i only let this happen if the other dog is well natured), and during these times, he completely ignores anything i say or any commands i give, he wont even stop for a treat. I literally have to drag him away or wait for said person or dog to go out of sight before i can attempt to resume the walk. But only when i am heading home will he finally walk well.

I would like to add he has done this since the first walk we did which was after his second vaccination, it has only been two weeks, am i expecting too much too soon, it's just i though Labradors loved to walk. Regardless of the problems walking i still walk him every day, it is only once a day at the moment and not for very long as don't want to push him too much if he's not enjoying it, I'm keeping it to a 10 to 15 minute walk round the block at the moment.

Please, can anyone help with this?

Answer
Your problem could partly be due to not getting him out sooner.  The period between 6-12 weeks is a dangerous time.  One sniff where a sick dog relieved itself in the last 6 months can bring on parvo or another life threatening disease.  Fail to expose it to strangers, including men, women, children, noise, etc. and you could end up with a misfit you can't take out in public.  They also need continuing contact with other dogs, but it must be limited to ones you know are getting good care.

If getting out in front and coaxing doesn't get a puppy moving, try dropping behind it and running by in baby steps calling ''Go, go, go!'' In a happy, excited voice.