When companies hire, or a university accepts a student, they want to see extra curriculars to get to know who YOU are. The best piece of advice I have ever received is that companies/ managers/ etc. don't hire just for the role, they are hiring for a future peer and leader. So as a person, being multidimensional allows you to have conversation starters and allows you have a way to connect with folks outside of the job itself.
If there are specific careers you definitely want to do (Doctor, engineer, lawyer, electrician, etc) see what clubs or groups you can get involved in to further learn and enhance your network and mind, but also use it as a way to develop your personal skills. Easiest way to handle extra curricular is to not treat it as a resume builder. The more you love something, the more likely you are to get further involved and invest time and energy, which will help in the long run!
Your schoolwork is a minimum qualification that your employer looks for. For all intents and purposes, everyone will have the same education as you.
Employers want a full person who does more to improve themselves and their communities than the bare minimum.
Just join a club or two and volunteer a little. Meet people. Learn about yourself. Find fulfillment in doing more than the minimum, get a decent GPA, and an employer will (hopefully) recognize you for it.
You have gotten some great feedback already. I wanted to make sure that you consider extra curricular activities as a way of gaining experience or connections that you might not get in school. Extra curricular activities require you to apply knowledge and thereby gain experience that you can then use in college and in the workplace. What I would recommend to anyone to do this is volunteering. Volunteering is a choice based system. You choose where to spend your time and what work you do. So invest in volunteering activities that you think will hone or improve a skill that you have. (If you want to be a teacher, volunteer to teach people something, like reading or dancing or some ob skill that you have.) Volunteering can also be great networking opportunities. You will meet people that you may not meet in any other way. And sometimes you will meet someone who is hiring in a job role that you are interested in pursuing. Or maybe they even do the job that you want to do. This connection can be an important resource in the future.
Like working with kids as a volunteer or a tutor? Perhaps you might excel in the field of education!