Controlling ALL thoughts?

Is it possible to control ALL your thoughts? What about the weird disturbing ones that just pop into your head? I understand how to choose the thoughts that I want to go with and let go of the others but I don’t know how to stop them from coming in in the first place.
Brooke says your mind is like a toddler with a knife, but at the same time says you can control your thoughts. If I could control the toddler then it wouldn’t have a knife at all!!
I’d really appreciate it if you could shed some light on this!
Thank you