Carol Patterson was waiting for a call from her doctor. When the phone rang on that afternoon in August 2011 at her home in Cortland, Ohio, it wasn't a physician on the other end. A woman named Robin said she was representing the American Diabetes Association.

Robin didn't ask for money. She asked Patterson to stamp and mail pre-printed fundraising letters to 15 neighbors. Both of Patterson's parents and one grandmother had been diabetic, so she agreed to do it, Bloomberg Markets magazine reports in its October issue.

"I thought since it does run at the family, it wouldn't hurt for me to help," says Patterson, 64, a retired elementary school teacher. She guessed, based on what she knew about charity fundraising, that about 70 to 80 percent of the money she brought in would be used for diabetes research.