1) Ask yourself what really drives and interests you about finance, is it the fast-paced nature, the challenging aspects or working with data that really drives you
2) Whatever your reasons, make sure they are relevant to the finance role you are applying to and support your answers with previous experience that highlighted your enjoyment of each aspect.
3) Demonstrate to the interviewer that you are passionate about finance, so try and sound as enthusiastic as possible in your answer and comment on your genuine interests that drew you to a career in finance.