Your thinking, and mine, affects reality.
But this makes no sense to Modern Man, because he regards thinking as a (probably epiphenomenal) brain activity - confined to the skull.
And probably merely neural activity that is a consequence of other causes (e.g. biochemical, genetic - or socially conditioned).
Also because he has a false understanding of 'reality'.
When providing arguments to support an understanding very different from that which is mainstream, habitual, unconscious and based upon unacknowledged and unexamined assumptions... chances of successful persuasion are slim!
But a particular argument may chime and resonate with a particular individual, and begin to free him from his invisible and self-made prison.
1. We tend to regard reality as out-there and by definition un-influence-able by our ideas about it...
Against this is that we may remember as young children having the built-in assumption that our thinking could influence reality; for example, that thinking about a scary thing could make it happen to us. That that wishing really hard for some-thing might make it happen.
This might perhaps be explicable in terms of an evolved instinct with some advantage to reproductive fitness; but it might also be understood by a Christian, as built-in knowledge provided us by God, our beneficent creator.
2. Then there is a very different argument that the totalitarian leadership of this modern world certainly seem to believe that thinking can affect reality; in the sense that they focus on detecting, punishing, correcting what Orwell termed 'thoughtcrimes'.
It might be argued that thoughtcrime is only a concern on the basis that thinking may lead to action - thus thoughtcrime may lead to crime. But in fact this link between thinking and action is never investigated or proved - and therefore it looks as if (for example) thinking 'racism' (in the modern mainstream sense of the word) is sufficient grounds for social/ media/ legal vilification, ostracism and punishment - even when no racist action is discovered; and despite there being no evidenced and coherent principle demonstrating that the modern-definition of thinking-'racism' leads to objective crime.
Clearly, the crime of 'racism' is a thoughtcrime - pure and simple; which implies that mainstream modern government operates on the basis that thinking affects reality directly.
(This 'spiritual' assumption of government will not seem bizarre to a Christian who regards the world as engaged in spiritual warfare, and the global totalitarian leadership as being on the side of Satan in this conflict.)
3. My last point is that a clearer definition of reality may help. Here, one must be religious and probably Christian.
Modern Man tends to regard 'reality' as ultimately dead, unanimate, matter/ forces/ waves/ particles etc. Physics.
By contrast he regards thinking as part of 'mind' of consciousness; restricted to living-things that have only recently (in the history of the universe) evolved - and might not have evolved. Thus an individual person - like you or me, alone, thinking something or another - seems vastly unlikely to be able to affect reality-understood-like-this...
But if we regard reality as Creation - our understanding may be very different. Creation is the product of a creator, a personal being, of God. And God (for Christians) is our loving Father. Therefore, we are - each and all - a part of creation - and divinely linked to it.
From such a perspective of reality as creation, it seems quite natural - and indeed necessary - that our thinking would be a part of creation, bound-up with ongoing creation.
And if we regard humans as having 'free will' or 'agency' - then potentially each person will be able to think from-himself; to think as a 'free agent'...
And in this case, a Man's thinking, which is already understood as a part of creation, will also have an effect on creation.
Putting together the above, we may reason that our thinking is always affecting reality-creation (for better or worse); and contributing to it - but that this affecting may be on a spectrum from unconscious and passive participation in creation to a conscious, active and chosen participation.
We may also see that we can chose to think in harmony with divine creation; or against creation - in other words to think in ways that subvert, destroy or even invert God's creative purposes.
This may clarify why evil totalitarians have such an intense interest in controlling our thinking. They are using our thinking to subvert/ destroy/ invert divine creation.
When a person chooses, or is duped, into evil thinking - this is what he does: he assists in the distortion of reality away-from divine creation.
Conversely, and positively; we may also reason that by making the opposite choice and rejecting the attempts of evil totalitarianism to control our thinking; we may instead choose to think in accordance with the purposes and meanings of God's creation.
Thus we can personally strengthen and add-to created-reality, by our thinking.
Creation-sustaining thinking is indeed the correct Christian understanding of what evil totalitarians call 'thoughtcrime'.