Because as of yesterday, I am CPR certified!
It was an all-day class that I took from the Red Cross. We got to practice on manikins, doing chest compressions and artificial respiration. We also learned how to use an Automated External Defibrillator. Those things are awesome because they tell you everything you need to do. There was a little bit about first aid and choking, but it was mostly CPR/AED.
I hope I never need to use these skills (at least not until I'm an EMT and it's part of my job) but I feel safer knowing that I could help someone, if need be.