So I thought I was doing a good job of leash training Wall-E, but then the past week he's been a stinker and refuses to be good on the leash. The difference I noticed with him is that he started to pull more and more on the leash when I walked him, so I switched him to a harness (we were only using a collar before) thinking that it would cause less stress on his throat.
Anyway, now when I walk him on the harness he seems to have regressed in his leash training

. He'll stop and sit down in the middle of the street and when I tug on the leash, he just goes limp and refuses to budge! I honestly think he hates his harness and is doing a silent protest against it!
So anyone have advice on training on a leash? How do you teach them to "heel" and follow where I go instead of him pulling every which way he wants to... oh and also, for those of you who run with your dogs, how do you get them to keep the same pace as you so they don't stop every 5 minutes to sniff something???? Please offer some training tips!
I've tried holding the leash real short so that he walks right next to me, but then he stops and sniffs at EVERYTHING so our 10 minute walks don't make it very far!