Efficiency
If you don't know what to work on, try to find what is fun.
Engaging. What comes easy to you. Why?
Because you are going to be more efficient at it. You will use the least amount of energy possible to do that thing. Which means that you will be better at it. You will be more efficient at the thing.
If you are forcing yourself to do something that is inherently boring or not fun, you are using more energy. This might not be something you truly desire. It might be a mimetic desire. You will naturally be less efficient at it. You will be swimming against the tide.