Question: Which effect is more influential, practice or motivation?

This question was prompted by me doing a lot of research on the zettelkasten. For those who are unaware, the zettelkasten is a note-taking system developed by Niklas Luhmann. It has 2 major parts: the index and the slip-box. The index is used to look up your notes and the slip-box contains your notes. The idea being that when you're working on a project, you read, write notes, and then actually apply those notes in your project. I think a lot of people, myself included, don't actually do this last step because "I don't have time to apply what I've read". This has led me to the question of, which effect is more influential, practice or motivation? When I apply what I've written down in practice, it really helps me to stay motivated, but since I use motivation as justification to buy new notebooks and pens that I don't really need, which one is actually more influential?