One good way to make yourself feel like you still have tests to pass and deadlines to meet that aren't entirely in your head is to involve someone else.
If you can find someone else interested in learning the same material, you're in the best situation. Set up regular joint study times, collaborate on the "homework", make up tests for each other at the end of the month, and you should be set. Of course, you'll still be more inclined to give each other leeway on the deadlines than a professor would, but the schedule should still be enough to keep the learning going.
If you don't have anyone like that, another option is to just find someone who's interested in learning anything else, doesn't really matter what, and make an arrangement where you try to keep each other on schedule. Tell each other you'll get through a chapter of your respective textbooks every week, or that you'll spend X hours studying every week, or something, and communicate regularly to check if you're meeting the goals. (If it's practical to still schedule shared study time where you both work on your respective subject and then go out for dinner after you put in your X hours, that can be nice!) Arrange a "test" at the end of the month - just have the other person give you a random set of questions from the textbook's end-of-chapter questions and check your answers with the ones given in the book (assuming the book gives answers! Find one that does, if possible) (note: it would probably be best if you can discipline yourself enough to not read through all the problems in the book so you're not prepared in advance).
Of course, the details of how all this should work depend a lot on your field and learning style, but hopefully you can come up with something that works.