CAS is an opportunity to apply what you learn, or employ skills that you may not easily get the chance to use in class. Leadership skills, collaboration, tackling a global issues, or experiencing the challenges of ethical choices are among the character developing outcomes within the program. Ideally, you will fill your CAS roster with what you want to do, or have always wanted to do. You should find things that are rewarding to YOU, and make your DP life more interesting.
In addition to this, many Universities look for the “well rounded student." The learning outcomes in this program just happen to be the exact same thing universities would like to see in an applicant.
You will realize that what you remember, and enjoyed the most from School was what you did outside of class. Service learning happens just outside your comfort zone, and with every experience, that zone grows larger.