What should I be thinking in a shift and how do I tell wich ones are real?

Recently,I've been experiencing a lot of shifts. So many,I actually doubt wich ones are shifts and wich ones aren't. I think the reason due to this is what I'm thinking during them. Sometimes,I'll be thinking absolutely nothing. But others,I'll be aware of my surroundings. And,when I'm experiencing a dolphin shift,I often think to myself 'go up for air' ect. I have absolutely no clue how to tell what ones are shifts or aren't.