Battery

The other day, I was about to head out on the trails for my annual attempt at completing a couch-to-5K program, when I realized that my iPhone battery was almost out of juice. I didn't want to risk having my phone die while I was out on the relatively deserted trails (what if I got attacked by angry squirrels and needed to call for help?) And I needed to leave the house soon or I wouldn't be able to complete the workout before sunset.