Dog Exercises Man

The problem with one of my favourite walks is that I can let Ava off the lead and she feels the urge to ensure that my back gets plenty of exercise. She will run along the roadside ditch and drop the ball and "ask" me to fetch. If she drops it and it doesn't go to the bottom then she picks it up and drops it again to make sure. I could leave it my too expensive an exercise and she won't join me on the walk home until I "fetch"