Remember the workout video she flew out to LA to do? She had to hike up the access road to the location--less than a mile of what would be an easy uphill walk for most people--then do her easy version of the choreographed routine for however many takes it took, and in the video it's obvious she's dying by the end of it. So even if she had a perfectly flat, smooth path, and a cool, overcast day, and plenty of opportunities to stop and rest and drink water, she'd manage to walk five miles only with great difficulty, and she would be in no condition to repeat that effort any time soon.