This question presupposes that the interviewer suspects how old you are (it is illegal for an employer to directly ask your age during an interview), and thinks they know enough about your work history to question if you should be making more money, or that you may not be in touch with your value in the workplace. Tell the interviewer that you are motivated by the quality of your work, the challenges, opportunities, etc, rather than being motivated by money. You should also convey that you still expect to be paid a competitive wage for the position you are applying for. (And if you don’t know how much you should be paid, do some research!!) Be careful to not show any negative emotion toward the interviewer for their assumptions about you. Don’t make negative comments about your former employers, such as, “they were tightwads”, or “the company couldn’t afford to give us raises.”