(didn’t save the right quote but)Not to be snarky here but if you need cpr and don’t get it your survival rate is 0%
cpr is not like on TV shows, something momentously bad has happened to you to need cpr , it’s a heroic last ditch effort to maintain a minimal amount of oxygen flowing to your brain and major organs until we fix what went wrong
the (unrealistic) depiction of survival rates following CPR on TV shows has been studied (and lamented as it gives patients families unreasonable expectations), including this excellent article from the 1990s which made it to the New England Journal:
https://www.nejm.org/doi/full/10.1056/nejm199606133342406
Upshot is that ~70% surival is not in line with the reality of 10-15%

Also, want to echo everyone’s support of getting CPR trained. I can’t tell you how many (or the percentage) of neurologically favorable survivors I have had probably owe that to chest compressions done effectively/immediately by a lay bystander.
the other thing to mention is that you don’t really have to worry about doing it at the wrong time etc. I’m sure Fisk and others can attest that we see are numerous cases each year (Maybe even monthly) where someone faints, is really asleep or drunk, etc and a bystander gives them CPR. You won’t kill someone. Usually if they aren’t dead they wake up pretty fast or moan or make some obvious signal that you should stop. Maybe they get a few broken ribs. But this is one of the reasons that they removed “checking for a carotid pulse” from the training for bystander CPR.
Final PSA - particularly for those who have their CPR/BLS training already. Consider taking the online or in person “Stop the bleed” training for lay people, offered by the American college of Surgeons. This is similar in depth to CPR training but teaches how to limit massive hemorrhage (ie, after mass shooting event, car accidents, even work related injuries etc). It is probably equally likely to help you save a life. The online class at least is free (though hands on is always better):
https://www.stopthebleed.org/