1)Entertaining the possibility you can make things happen with the power of your mind.
I think in order to do it would require a lot of concentration and focus and the need to block out external stimuli.
yes, things like: achieving something, setting goals, bringing dreams into reality…
I do not think anybody in history was able to do something with their mind.
The dead could or could not be watching us, who knows? I hope I find out very late 
I get these as well usually if I've been alone too long. I've experienced some things that make me want to remove my brain and sense organs and bury them lol.
My best advice is to rationalize the crap out of anything that you ponder