Here’s a hack - every day, before going home, go to a coffee shop.

Spend an hour studying for interviews there. This will ensure you have a fixed time to study.

Next, make sure you have a schedule planned out. Ensure it covers every important topic in-depth. You can follow a book like Elements of Programming Interviews, or take a self-paced online course like Interview Camp

If you have trouble staying motivated, those two things should help a lot.