Like many, I took four years of language (Spanish in my case) in high school. I enjoyed it well enough but never felt i was much past "the boy kicks the ball" type grammar.

Fast forward, and I realize that at about middle age, I don't have a compelling need to learn a language. But in a half dozen visits - purely for pleasure - to the Netherlands, I realized that I absolutely loved the sound of Dutch. So I started learning it on my own. And it has grown on me since. I took an intensive course earlier this year and now I've got several interviews planned in the Netherlands. I realize I've learned more in about 11 months of self-study than I did in four years of high school foreign language course.

tl;dr: learn a language you LIKE to hear, read, and speak!