The main thing to remember is to show enthusiasm for learning, and then talk about wanting to get the most out of all the opportunities available to you at university. Focus on the all-round experience that university offers, including your plans for joining specific teams and societies. This shows that you have done your research.
Your answer can be broken down into academic and social opportunities, but the skills learnt are transferable. For example, the leadership skills and responsibility needed as captain of the athletics team could be put to good use when doing group project work.