Books

I Want To Be a Mathematician, by Paul Halmos

"A good stock of examples as large as possible is indispensable for a thorogouh understanding of any concept, and when I want to learn something new, I make it my first job to build one."

"Here you sit, and undergraduate with a calculus book open before you, or a pre-thesis graduate student with one of those books whose first ten pages at least you would like to master, or a research mathematician with an article fresh off the press - what do you do now? How do you study, how do you penetrate the darkness, how do you learn something? All I can tell you for sure is what I do, but I do suspect that the same sort of thing works for everyone. It's been said before and often, but it cannot be overemphasized: study actively. Don't just read is, fight it! Ask you own questions , look for your own counter examples, discover your own proofs. Is the hypothesis necessary? Is the converse true? What happens in the classical special case? Where does the proof use the hypothesis?."

The Art of Mathematics, by Jerry P. King

This is a description.

Letters to a Young Mathematician, by Ian Stewart

"Mathematics is a product of human minds but not bendable to human will. Exploring it is like exploring a new tract of country; you may not know what is around the corner, but you don't get to choose."

YouTube Channels

3BlueOneBrown by Grant Sanderson

Here

ThatMathThing by Joel Rosenfeld

Here

Podcasts

In "Is there Mathematics Beyond the equal sign, the speaker talks about different ways to learn Mathematics. One way is to look at examples and then develop a general theory to understand the examples, the other is to study the general theory and use examples to understand the general theory. She also mentions that Mathematics is not just a sequence of hurdles, getting higher and higher, but rather as network ideas, where you can approach a topic from multiple directions. The emphasis is that different people learn Mathematics with different approaches.