Being the Executive Committee, it is not only an item that can be written on your resume. More importantly, it is about relationship.
I am not sure if you have been the executive committee of particular society or not. I am not sure if you will and currently are part of certain society. If so, try to dig out different pieces from your mind. What are those? You can always find some relationship formed because of the society. I am not talking about the relationship with your boyfriend/girlfriend, (or that can be too if you have :p) but the relationship with other committee members, schoolmates and even with your society.
Honestly, I have a lot of good friends in school because of my society, perhaps because of preferential selection in Chinese culture. To be more generalized, remember and love your origin. The origin here is not only the society, but HKUST.
Last but not least, I want to show my love to the one I met here.