What a great question, annoymage, and your grammar is fine.
When I was high school age, my strengths were in writing, history, civics...that sort of thing. The way my high school was set up, you could get by with just the most rudimentary math and still graduate (the most advanced math I had in high school stopped at 'how to balance your check book' - no kidding). I hated math then, and I was terrible at science, so that's the path I took.
A few years out of high school I wanted to do exactly what you say, improve my weaknesses. So I started with Introduction to Algebra and found I really, really liked it. Then I took the equivalent of high school physics, and I *really, really* liked it...I just wasn't as good as other students at it.
I ended up majoring in physics (it took a while though

), but it was a real battle.
But I don't necessarily think my choice would be the best choice for everyone. I often wonder about the other paths I could have taken, had I studied something that came easier to me.