running with my lab

Question
We have a wonderful 4 year old yellow lab. She walks with us everywhere and goes for 3 mile walks almost every day. When at off leash parks she will run just fine on her own or with other dogs. But if we try to get her to run with us--on the leash--she will go for a very short time and then will lag way behind and we have to pull her. I know she is in good shape--she just doesn't want to run. We live by a lake with great running paths and would really like to train her to run with us. Any suggestions on how to do that? Thanks!

Answer
Have you tried treats?  Don't try to run and hold one out.  Just slip her one once in a while to let her know you have them and it pays to stay near you.  

I guess you could try what I do with young puppies just learning to walk on leash.  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.