Being a detective is a very demanding job, and you must show the interviewer that you can handle the physical and mental components of the role. Talk about your actions to ensure you are in good physical and mental shape, and discuss any challenges you may have. If you have an injury or issue that would compromise your ability to work as a detective, the interviewer will not necessarily pass you over for another candidate, as that could be discriminatory. However, they may be able to find a way to work with your physical abilities until you are healed from your injury.