Show them that you have considered other alternatives before making this decision. Point out how this job satisfies your career objectives. Let them know that you understand their challenges, that you offer a solution and that you really want the job. Identify a weak area. Tell the interviewer that you view a weakness as a challenge.
Challenges are what allow a person to grow.
Cite an example to show how your style is similar. Give them an example of an average day in your life. Highlight the fact that you set daily goals, but are still flexible. Carry a daily organizer with you. It is easier to keep a customer, than to replace one.