the mind > emotion > pleasure > cheerfulness > be cheerful [verb (intransitive)] > assume expression of cheerful liveliness (5)
transitive. Of an expression or emotion: to cause (the eyes, face, etc.) to appear more lively or animated. Frequently in passive.
intransitive. Of a person, or a person's face or eyes: to become more lively or animated; to brighten.
transitive. To make (a person's face, eyes, etc.) animated or lively; to light up, brighten. Also with up.