Good Morning America's Amy Robach is a keen fitness fanatic, regularly documenting her runs around New York on her Instagram feed.MORE: Amy Robach surprises fans with appearance in reunion pictureThe presenter doesn't train alone either, as she regularly partakes in the exercise with a group of friends.And on Monday, the star surprised fans as she announced not only an expansion to her running group, but an incredible goal they were training towards.WATCH: GMA's Amy Robach impresses with healthy