A new favorite quotation of mine about mathematics learning:
"Mathematics must be written into the mind, not read into it. 'No head for mathematics' nearly always means 'Will not use a pencil.'" Arthur Latham Baker, Elements of Solid Geometry (1894), page ix.
Hat tip to the Bay Area Math Circle for the quotation reference.
To put things in perspective, and to possibly invalidate the general application of my insight on the matter, Calculus was in fact the only course I passed my final semester of high school. I received a D shortly before I dropped out altogether. The D score was earned only after being the only student to ace the final, a task which was itself only possible after I proved the first fundamental theorem to myself (thanks to an especially verbose description of it in one of the exam questions) during the course of the test.
To this day I find that the actual solving of equations to be tedious and can only be interested in problems tenable to axiomatic and algorithmic approaches. Thats where all the fun is imho. Who cares about actually determining a number (or equation)? [the answer: all the smartest people do.]
I'm serious though, I'm learning with textbooks, etc.. and I'm a dropout so I have some of the basics already.
In my first year of a doctoral program, I could study from after lunch until next morning and I concentrated on getting the fundamentals right. The greatest book, the one where things began to click, was Rudin's "principles of mathematical analysis". Before I came to this book, I had wasted a lot of time finding my style of learning or, if you will, discovering my preferences. But if you already have the basics and are not going to waste as much time as I was trying to figure out what is what, you might pull it off much quicker.
Good luck! To me it was a cool time and I finally got rid of my math inferiority complex ;)