one of the things the army will tell you about CPR is that you should continue until you are no longer capable, or a medic has relieved you

they also say you need to push *hard*, and if you break the casualty's ribs, no fucking problem, their heartbeat is much more important than the shape of their ribcage

this is important advice imo

keep pushing

keep your friends and loved ones alive

do not stop until they are cared for or breathing on their own