I mean, the thing about autism is that your 'natural behaviours and feelings' can be things that others find deeply offputting, like hand-flapping or other strange repetitive movements or sounds, anxious skin-picking, avoiding eye contact etc. But not doing those things requires conscious effort, because they're natural to you.

So it's kind of like going through social interactions with an itch that you're constantly aware of but can't scratch. Or perhaps for a neurotypical person, imagine that you're instead not allowed to make any facial expressions or change in your tone of voice and you have to constantly monitor yourself to make sure you're not doing what is, to you, a normal and unconscious reaction. Of course everyone has to modulate their tone of voice and expression to some degree, but with autistics the gap between how they'd behave 'naturally' and 'what is considered socially acceptable' can be a much bigger one to bridge.