If you want to get out and exercise in Sydney go to the Royal Botanic Gardens. It's free, pretty large, and plenty to look at. Bring a hat though because even with all these trees there is little shade. I walked for 1 hour and probably only got through 40% of the trail. There's a walk along the water that provides a good breeze
You can also get your Sydney Opera House and Bridge picture out of the way here.
For being so close to the harbor and the docks the water is fairly clear and blue.
Looking across to the city. Next time I have a few hours free in Sydney I'm going back to see the other half of the park. Check the weather. I was here from 2:30 pm to 3:30 pm. At 5:00 pm a thunderstorm broke out and everything went from blue and dry to gray and drenched.