One enjoyable mid-day walk is to walk parts of Prince's Island Park and maybe climb the stairs at McHugh Bluff. It's good for the calves and when I got to the top, I felt that my huffing and puffing was well earned (especially after a heavy Lunch). Another payoff is the view and the desire to go back down and try it again!
The last time I made the climb, there were some pretty hard core folks working the stairs. I watched one guy time himself repeatedly as he ran up 2 of the flights at full speed. I saw another sprint the entire 167 stair length. I admired all that action and then decided on a gentler approach of wandering off on one of the other various pathway choices that the Bluff has to offer.