Ahoy there. I am twenty years old, and have (as a result of my interest in cosmology and astronomy, and the natural sciences) developed a keen appreciation for mathematics (in physics, primarily). I have always had an interest in the sciences, but lackluster teachers and personal disinterest (on account of not understanding) has left me with atrocious math skills. I imagine I would currently fail any math test given me beyond an 8th grade level - and even then I might struggle. Unfortunately, I haven't the time to attend a college - nor do I need a degree of any kind. I am purely interested in self-betterment, and properly increasing my understanding of certain things including but not limited to: cosmology, astrophysics, quantum physics, relativity, and all that funky business (and general everyday-life-related applied mathematics, if I can slot it in there). I need some advice as to how I ought to approach self-teaching. I have an account on Khan academy (though I'm well aware that some dislike the site), and have purchased many books on the topics that I plan to learn, but I feel it will be insufficient, as I have poor memory retention. I have started reading Kline's "CALCULUS - an intuitive and physical approach". Can anybody provide any detailed advice specific to my situation? I'm even willing to join flexible online programs, if such things exist outside of online colleges. TL;DR I'm 20. I suck at Maths, but wish to change that. I love science, and science is whence my interest in math. I don't have time for classes. How do I self teach effectively?