Why can't we learn what we don't like?
1
There is some relation between what we are interested in and what we are good at. If people are bad at something, they usually lose interest in it and turn to other things. If you are good at something, you enjoy doing it and are interested in it.
Interest, therefore, is a preditor of ability, and you are better at learning things that you can do, than you are at learning things that you cannot learn to do.
2
Learning requires time, attention, and effort. If you are interested in something, you will (want to) spend more time, attention, and effort on it. If you aren't interested in something, you'll find every minute of it unpleasant, so you will limit the time you spend with it, not be as attentive, and not labour as hard.
You will also not think about it while you are not learning, you won't connect it to other interests and activities, and so on. In short, you won't elaborate.
There is a psychological theory, the elaboration likelihood model, that says that the processing of information will be more superficial when the motivation to process the information is low.
3
Doing something interesting is pleasurable, and everything in your mind and body works better if you are in a good mood. Hormones such as oxytocin, whose levels are higher when you are &quot;happy&quot; (and free of negative stress), have a positive effect on memory formation and retention.