Number one I must commend you for the amazing gif. of Kath and Kim, absolutely hilarious! Back to the question, an awesome place to go for a power walk in Sydney is the Coogee Beach to Bondi Junction walk. It is a relatively long and hilly walk, but once you complete it the satisfaction your left with surely overpowers. The walk however does inhabit both tourists and die hard fitness fanatics so if you are after something more quiet there are some nature trails near Bundeena in the Royal National Park. The smell of the trees is amazing and a day here really does cleanse the body from the toxins of the city.