What could you do in a relationship to keep the spark and make it last longer when you are young?

Keep it new and exciting. Don't just go to the movies and dinner; Go to concerts, baseball games, and picnics. It is hard when you are young to keep a serious relationship alive, but if you and your partner want it enough, it will happen. Spend time together, but not TOO much time. The longer you are with them, the more comfortable and trustworthy you will become. I don't know how young your talking, but keep the sex interesting, that will keep the spark alive!