And you are free to do that, because mind-reading still isn't invented, and any rules about thoughts are still unenforceable. And I hope it stays that way! You can't make yourself not think of something. At least, I can't. I suffer from intrusive thoughts, and they just pop up from nowhere. I can (and do) try not to dwell on them, think of something else, go do something else, and they pass; but I can't prevent myself from thinking them in the first place, however much I wish I could.