When a person's heart stops beating, they do not immediately die. Compressing their chest will supply oxygen to their brain while you wait for the paramedics, and could easily be the difference between life and death. Thousands of people have had their lives saved by this technique.
The Challenging Part
The most challenging requirement of this honor is probably this:
1. Successfully complete a class sponsored by either the American Heart Association, the American Red Cross, or an equivalent under a certified instructor in order to properly learn and demonstrate one-person CPR. This must be within the past 12 months.