It's all getting too much.
We all think about stuff, worry about the who/what/where/when/why's, sometimes it's rational, sometimes the situation is controllable; changeable.
Other times we can't do anything about it, or we're over-thinking and worrying unnecessarily. Like when you leave the house empty and you think "those people who were watching you get out the house will rob your house" (someone said that to me today! lol)
During those times the best thing to do is stop worrying.
I've said "It's hard to switch off your emotions" and "you can't just stop!".
But that's not true.
You can do things to take your mind off it, keep yourself busy, but that isn't facing the problem.