Muse, I changed my major in college in my senior year (1971) and graduated in a wholly different subject than I expected to. Back in 2001 I started thinking about what I'd "regret" in another 25-30 years when I'm toward the end of my life and realized I still loved my original major subject so I went back to school and I'm getting a second BA in "my" subject next month :-)

The secret of the difference? Being interested in what I'm doing and doing it only for myself and because I want to do it. Oh, my new/old major is history :-) Whatever you are doing, whether history or reading or subjects you like or don't like, find an angle that is "yours" and go at it from there. I was taking a boring course and had to write a paper to "correct" a paper I'd already written! I wrote it entirely in verse/poetry! Took forever but the "challenge" kept me going and interested and, of course, since I was concentrating so hard to "translate" the material into poetry, I learned it extremely well.

Read your history "backwards" :-) Start from the end and go right/bottom to top/left. Figure out a "gimmick" that interests you and makes it fun but challenging and you won't mind so much doing what you need to do. If you like science/math better than history, for example, find a novel about a scientist or mathematician of whatever era you're studying in history and place them in the period and learn about the period that way. How did X war or ruler influence your guy? Read a section of your history book then read a section of the novel and see if you can "find" where they intersect. The "interesting"/personal bio will help you remember the rest. Get yourself involved. If you're learning geometry, have your father help you "build" something with all those angles and shapes (I recommend stairs, I have a hill I wanted to terrace and was working at how to do that with my husband's mathematical help) so it "clicks" in practical ways outside of a book. The more ways you can "see" something the better you'll understand/remember it.