I plan to go to graduate school in applied mathematics. I am looking for internships in theoretical or computational math, physics, or a related field that can be a good precursor for going to graduate school. I am looking to do something exciting but not over the top because I am relatively new to theory and computational work (I am probably first year grad level). Have anyone had good experiences in companies, national labs, or jobs unrelated to research like writing or education? What aspects of the internship are important for my goal?