Glad to see you're feeling better. How amazing to get to go to China! (I'll try not to be too envious.)
I think you have a great idea by getting involved with as much as you can and do well in school, etc. As for the motivation part, what worked for me when I felt unmotivated was doing things that I didn't dread. (Since, at the time, there was really nothing I really
wanted to do.) After a little while, certain things became more fun or empowering, and I'd get a glimmer (just a glimmer) of motivation to do it a little more. I grabbed onto every little bit I could, and just kept doing those things. Now, many of those hobbies and activities are mainstays in my life today that I
love to do, and there aren't enough hours in the day to do everything that interests me!
One other thing. I remember being 14 years old. It sounds to me like you are handling it
way better than I did. But there's no doubt that stuff is changing in your body (think hormones) that will contribute to these feelings of apathy and lack of motivations. They sure did for me. But the thing to remember is that it
will pass.
Hope that helps.