You have to work really hard, bud. You can't be a slacker when it comes to this stuff. If you don't understand something, you better make sure you learn it as quick as possible, otherwise you'll always be behind.
You need to have a assumed knowledge in mathematics, physics and information technology.
Not sure how things work outside of Australia though. But in high school, we have classes that cover all these things (like general things) that help you understand the fundamentals when you start. But believe me, it'll get harder beyond belief so you better be prepared to organise your times in order to catch up and learn everything.
I'm in a screwed position myself because I enjoy clubbing too much, and going to music festivals and concerts. I'm behind quite a lot of work and it's not easy to learn engineering content overnight.