When Amy McDonald went door-to-door, inviting neighbors to give her their grocery lists, she found 89-year-old Jo Trimble pale-faced with a stomach ache. When she returned with the groceries, Trimble had become worse. Instead of walking away with simple get-well-soon wishes, Amy called 911. Turns out, Trimble was having a heart attack. Paramedics arrived just in time, USA Today reports.