True - there are many things you can't decide. Life does not owe anything to anyone.
On the other hand, there are many things that you can do/decide.
There is no easy path - some challenges will hit, some challenges you will choose on your own.
There are ways to influence your life to a better overall experience.
Think about what a "perfect" day would look like in your best possible life.
Then divide that day into multiple elements and achieve them bit by bit, goal by goal.
When you make up your mind and start working on something you want in your life, opportunities will show because your mind will automatically start looking for them.
When you se such an opportunity, seize it. It will help you achieve the results you want.
It won't work until you apply conscious actions towards improving your life daily.
You also have some control over things - apply yourself on the things that you can do better.
The rest will line up in a matter of time & persistence.
About school, something that helped me learn better is studying to understand the material better (not just for the grade). If I look deep within myself, I enjoy learning new things and even the most boring material at first sight has me asking questions inside - It has motivated me to seek to understand better. Even if some material is not necessary for you right now, you never know when something basic can turn into something useful later in life.
If you believe a class is getting boring, you can help the whole class by asking interesting questions that the teacher can answer... seek the elements that make you curious and every subject will start to feel easier to manage.
After High School, if you choose to, you can pursue higher education or specialization in your personal interests; however, even if you study in the field you like, you may come across a boring class... having the discipline to organize and absorb the material by finding ways to make it more appealing to you (regardless of the kind of teacher) will help you succeed where others lose interest.
Wishing you success :)