because:

• when it’s cold out, the plastic NYTimes bag of warm poop in your pocket makes a fabulous hand-warmer
• you meet the neighbors who have completely ignored you all those years you went jogging past
• you get to stop to offer treats and not have to admit to yourself that you’re so out of breath you’re wheezing
• if you talk to yourself, people think you’re sweet and doting instead of nuts
• neighbor kids are interested in your dog instead of worried that you’re one of those strangers with candy they’ve heard about
• in normal life you can deal with those awkward periodic silences by reaching into a pocket, any pocket, and offering dog biscuits to your friends