I'd describe intrinsic rewards as "the thing, in and of itself, is enjoyable" and so if you're motivated primarily by intrinsic rewards, then doing anything that doesn't tickle that part of your brain tends to be somewhere between difficult and impossible and it's often the fear of punishment that finally forces you to do something. This is basically ADHD in a nutshell: can't do the thing because it's not fun, but oh crap the deadline is tomorrow so it must be done now because otherwise failure/get fired/etc.

So it's not so much about incentives or rewards, but that some people are motivated by things that aren't straightforward to control. Can you make unenjoyable tasks enjoyable? Maybe, if you understand that's the issue in the first place, and whatever it is that triggers that for you is something you can add to a task. e.g., a very common ADHD hack is doing something for other people - if you find it difficult to clean just for yourself, but you have guests coming over? Suddenly you're a cleaning machine; or perhaps you struggle to do boring, repetitive tasks in silence but add some music and off you go!

This is, incidentally, what makes being a manager actually challenging. People who are motivated by extrinsic rewards? Probably not super-difficult to motivate (raises, bonuses, public recognition, promotions, etc, are all tools for this). People who are motivated by intrinsic rewards? Well, that's a bit trickier, and I'm not sure what tools a manager would have available to them in this situation.