unfit
adj.adj. not in good physical health or not suitable for a specific purpose. You use this to describe someone who needs more exercise or something that is not good enough to be used.
adj. not in a suitable condition or of a sufficient standard for a particular purpose; lacking physical health or athletic conditioning. Often used predicatively after a linking verb.
He felt very unfit after taking the elevator instead of the stairs.
The building was declared unfit for human habitation due to severe structural damage and mold.
Despite his technical expertise, the committee deemed him unfit for the leadership role because of his lack of interpersonal skills and history of poor collaboration.
From un- + fit.
Often followed by the preposition 'for' or a 'to-infinitive' ('unfit for purpose', 'unfit to lead').