Yes, this is typical lab behavior! Have you considered dock dogs for Harmony? Does she like to play ball? You could always enroll her into fly ball or agility. Lure coursing is also an option. It just sounds like she needs something more to do than just walking. Do you have a treadmill? You could always wear her out on that when you aren't able to exercise. Does she like to swim? Maybe you could take her to the lake/beach to swim or if you have a pool!