refusing to go on walks

Question
My 11 month old yellow lab will often resist and refuse to go out on walk with members in our family to the point that she will lay down in the middle of the street or driveway and force us to pick her up and carry her.  She is a very eager and active retriever when off the leash, and has demonstrated no signs of injury or discomfort when playing with our neighbor's 2 labs. I can't imagine why she would refuse the chance to exercise. Help.

Answer
Is she only refusing with SOME family members or with ALL family members?  Something could also have happened where she is afraid or it wasn't fun.  

Maybe you can retrain by putting the dog in the car, drive a few blocks away, and then lure the dog with treats back home.  Or change the walk so that you walk towards something fun, maybe if a park or open area is available, so it leads to some play time.  

If it seems that she is balking with specific family members, you might want to consider formal obedience class and have those folks do the training.