Set on Doing Something

You can set or put something down somewhere. For example, i'm set on taking the exam. That means i'm strongly in favor of it. I've made my decision, and that's what i plannd to do. What would be the opposite of set on doing something? Craig, set against doing something? So against would be, in spanish, maybe contra. You don't want to do it. But i'm definitely set on travelling somewhere next year.