Here's the chance to really sell yourself. You need to briefly and succinctly* lay out your strengths, qualifications and what you can bring to the table.
Be careful not to answer this question too generically,** however. Nearly everyone says they are hardworking and motivated. Set yourself apart by telling the interviewer about qualities that are unique to you.
succinctly* = in few words
“Successful research firms can command substantial fees, and buyers demand clear, succinct and unequivocal analysis and predictions.” — Zachary Karabell, Newsweek, 9 Mar. 2009
generically** = generally, commonly