Grocery shopping can be a logistical nightmare for the elderly: For those who live in cities that were originally designed to accommodate fit, mobile pedestrians, it's a pain to schlep bags down the street and on and off buses. Older folks in suburban or rural areas usually can't walk to the nearest grocery store, which is even harder for the ones who've had to give up their license. This is why seniors often resort to high-sodium processed foods from the nearest convenience store. Many cities have volunteer programs where you can shop for someone less spry while picking up your own groceries; check VolunteerMatch.com to find one in your area.
Calories burned: 210 for an hour of shopping and 15 minutes of putting groceries away (you'll burn 89 more calories if you carry the bags upstairs).
Muscles worked: Quads, calves, biceps, shoulders (lifting, carrying, reaching up to shelves and cabinets, walking and climbing stairs). To maximize the burn, take multiple trips from the car or up the stairs, carrying lighter bags but moving at a faster speed.
Karmic bonus: Someone's world feels a little cozier.