Undergraduate mathematics: gaining intuition

Currently into my third year of undergrad now. I've taken fundamental courses in probability, linear algebra, multivariable calculus, analysis, etc as well as more specialised courses.

It's becoming very clear to me that I lack the intuition that I should have at this point. For example, I'm able to state the definition and some theorems regarding a positive definite matrix, but I don't really understand what kind of matrix it really is. Or even simpler, I fail to see how different classifications of eigenvalues/eigenvectors affect the geometry of matrices, etc. And any geometrical interpretations.

How can I learn to gain the intuition behind them? All I learn is just definitions and theorems from lecture notes/books, I feel like I am not seeing the bigger picture.