You'll be full of great advice for this person, based on your own life experiences. Your life will naturally serve as an example to them. You'll relate to their struggles and emotions, and you'll be a big help to them in terms of illuminating their proper path in life -- their career, schooling or whatever else they're trying to achieve -- and in mapping out a viable plan for pursuing their goals.
You'll inspire them to work hard, and sometimes, when inspiration alone isn't enough, you'll make them apply themselves. You could take on the role of taskmaster to your pal, which will definitely blur the boundaries of friendship -- being equals versus being teacher and student. But in general, you'll inspire each other, and this aspect will strengthen your friendship.