In limited situations, discrimination based on age, sex or some other protected factor is permissible if the employer can demonstrate a truly compelling reason to discriminate.

For example, a religious organization may refuse to hire or promote someone not embracing the same religious beliefs; an employer can refuse to hire a man as an attendant in a women's locker room; or a person with an extremely heavy accent, originally from a non-English speaking country, can be denied a job requiring excellent English communication skills. Employers are advised, however, that courts are reluctant to permit such forms of discrimination.

You would be on safer ground describing the rigors of the position (e.g., "need to be able to lift 200 lb. boxes and store them at a height of 6 feet") and focusing on the needs of the position, rather than describing the kind of person you want to apply for the position.

Let the applicants self-select whether the work you’re offering is something they’d want to do.