In most Hindu/Buddhist philosophies there are six sense - the mind, not as some psychic ability, but really as a 6th sensory input. From that POV then we do not own any thoughts, just merely observe them from some separate awareness.
Such an attitude would make it harder to follow any actual projected external thoughts. How hard that may be in reality, I can't say. I recall Steven Greer mentions a psychic attack he was able to repel, using a similar technique. So one cannot push the waters back, but to realise you can let them wash over you without being swept away. Subtle and powerful, and hard.
But from what you are saying, that none of the thoughts are our own, then maybe that's the test - to ignore them all. lol.
I may also have mentioned this before. I came into the possession of a unique volume pf psychiatric notes from 1895. This included one guy who claimed the gov agents were sending waves into his home and beaming thoughts into him and his family. 1895!!
I've tried really hard not to get to deep into the energy aspects of this. Some of my more personal experiences would be considered crazy, and coupled with things I've read as well as patents I've seen it has occurred to me in these recent years the crazy ones are those who don't view this as not only possible but taking place all around us both naturally and unnaturally.
One example I'll share here is I rarely remember dreams. Two that I remembered were made memorable because something/someone in those dreams wanted me to wake up in the dream and understand it was a dream. Both times resulted in my waking up in a panic. I believe because it did occur to me that it was a dream and there was an intent outside myself interacting with mine on that kind of level.
I don't mind going into the energetics, but very much up to you what to share in public.
One other thought may help. We don't usually think of our thoughts as having a location - we think of thinking "in our heads" but don't localise it any further. When I was "stuck in the void", and had regained my thinking skills, it was interesting that the thoughts were way off in a corner. Amid the expanse of awareness this little voice seemed quite far away. Was me, but was only a part of me.
Thus from that POV it made sense this idea of thoughts being some input, rather than defining our self, in some Cartesian sense. The effect lasted maybe a couple of days - shame, as there is training to try and stabilise that condition. Vision was also impossible to play that "at a distance" routine - too much in yer face!
Anyway, just thoughts on means of protection.