Some people will realise that they are dreaming while the dream is happening

That is true; after becoming aware of the fact you are in a dream, not knowing how to wake up, I suspect it is a frightening experience. On the same token, by becoming of your inward presence, you have the ability to change your thoughts, and can change the world inside of your head. These are called lucid dreams. If you ever become aware of the fact you are inside a dream, what would you do? Would you try to wake up? Would you try to make the world of your dreams? Even if you wanted to, do you think you'd be able to? If you wish to learn how to experience lucid dreams, there are many tutorials online, teaching you step-by-step how to lucid dream.

when in a crucial situation, after calling 911, the correct posture for delivering effective compression is the proper hand placement.

first, place two fingers at the sternum, then put the heel of your other hand next to the fingers and place hand on top of the other. lock your elbows by using your body’s weight and compress the victim’s chest with a depth of 2 inches.

moreover, do 15 compression and 2 breaths, this process must be done four times until there is a pulse or a arrive.