In the absence of wonder, add novelty
While thinking about learning, I had a flashback to when I was 11 and learning Basic programming for the first time. Flash forward to now, when I'm trying to learn React Native, and I can't seem to get going on it. Long story short: it takes small steps to learn something new. If you are young, it's easy to be entertained by these little steps. When you get older, the novelty has worn off. So the solution is to add novelty to it. For example, when learning guitar, you learn one chord, then mess with it for awhile in any fun way you wish. Then add another chord, and make that fun as well. Review sessions should also be fun. I should be cautious here, as I sometimes fall in love with the "magic bullet fallacy" where I think a simple solution will solve the entire problem, and often it does not. However, I do find the hypothesis compelling. I don't know if this will work, but I think it's an idea worth trying.