“Write a letter to yourself at a certain age. Is there anything specific you would tell yourself? Is there anything you know now that you wish you knew then? Let yourself know!”
Do not waste your summer vacations sleeping at home, this time is very precious. Try to explore new things and new fields to see what you like. Do not just think about choosing a career field based on its scope in job market and its salary potential. Otherwise, you will end up having a very frustrating and boring life.
Other than that, try participating in as many extracurricular activities as you can. These will build your confidence, self-esteem, and will be very beneficial. And the stage you are in, is the best stage in which you can learn these skills.
Do not be afraid of trying new things, meeting new people, and learning new skills. Because later on in every stage of your life, you will work with new things and meet new people. If you will be in habit of all this, It will not be a big surprise for you.