I hated math until I realized I could actually use it in the real world, long after grade school. After finishing the ordeal of college algebra, which I loaded at the end of the degree knowing I'd struggle, I started looking for ways to use it.

I tried to use systems of equations to identify an opponent's strength in a web game (Astro Empires). This was with a post in the forums, so people could come and discuss it. It was actually a little thrilling to have people who didn't know about systems say I was doing the math wrong, then see people who routinely did much more complicated math commend me for my effort (while explaining why it was futile).

I can never remember "correct" formulas between uses, but now I always think in terms of algebra when I need to solve a problem. I can come up with a functional formula on the spot.