In my world, I have a character with telekinetic powers. She's able to lift objects with her mind and apply quite a lot of force to them. To put things a bit into perspective, telekinesis in my world works a bit like a physical workout, as in a character can tire themselves out if not careful.
My character, however, is quite a prodigy, being able to lift multiple objects with ease, she's even able to stop a few bullets if she braces for them. Let's say the maximum weight she's able to lift is around 2 to 3 tonnes, heavier objects will cause a lot of physical strain, to the point of the character passing out.
I want the character to be strong but there's a problem: in a fight, my character would simply be too powerful. She would be able to take control of the enemy's body. For an enemy to even have a chance, her telekinetic powers would have to do no/or limited effect on the body itself.
I don't want to simply say "in this world telekinesis just works like this" and call it a day.
So what biological process, even if it requires a minor change to human biology, would allow interference with telekinetic powers?
To explain a bit more about this world: people with powers like telekinesis or similar are not very common, but there's still quite a lot of them around the world. Most of the time they get captured and used as weapons though :(
Telekinesis works kinda like training a muscle. You can train it and become better. You can increase the amount of "force" you can apply to matter, but more precise, delicate movement would require more expertise, and different kinds of traning. Resistance to the great physical strain it gives can also be reduced (at least the "feel" of it), but it's still very risky to push yourself too much.
And to explain what a "good reason" is, it simply means a reason that makes what I've described impossible, or at least very difficult, so that no telekinetic user would just default to snapping your neck in a blink of an eye.