When you are learning a skill, you have what I call structure learning, free-play, feedback and deliberate practice.
The structure of the skill is the curriculum, so to speak - but the skill itself is an action. When someone is learning music theory, they are really just learning what the structure of the skill is. If they knew the series of actions they needed to take, the goals they needed to set for themselves in practice, and the relationship between those competencies - then they would have no need of theory. The theory informs us of what the structure is.
In most skills and hobbies, you don't need much theory. This is because people have created drills and identified the fundamentals over time. Everything has been organized for you.
That's the structure. Here's the interesting thing - you don't need much structure at all. If the structure is a tree or graph representing the fundamentals you need to master, all you need to know is the next node - the next skill you will focus on.
That's where practice comes in. Practice should be your primary focus, not your secondary focus. Some fraction of that should be "free-play", or curiosity driven exploration & synthesis. You add that in because it's critical for learning, and because it keeps things feeling fresh - but the real value-add is to learn to enjoy the practice. If you "play" at practicing, then you're golden.
Practice though, must be deliberate. You don't just "make music". You have identified something you want to work on, and you attempt it through repetition. You compare your effort to the end-result (using feedback), and you repeat. This loop never ends. If you feel you've mastered something, you move on to the next thing. If you don't know what the next thing is, then you turn to theory in order to identify it.
That's all the balance you need. Learning about a thing is not doing the thing. Do the thing. Identify what you want to work on, draw a little progress meter on piece of paper, and start doing it. Do it for 20 hours, filling up the meter. At the end of 20 hours, you have a choice: draw another meter for another task, or stop doing the thing.
The problem you face is thinking that motivation is your problem. Your problem is that you are not doing the thing. How you feel when you are not doing the thing is irrelevant. How you feel after you've done the thing - and you notice that it's not what you wanted to it be - is irrelevant. You will never be at the goal, that's the whole point of practice.