Use 'fighting fit' to stress excellent health, not just being okay or slightly well.

Health Emphasis

Imply physical vigor, suggesting someone could handle demanding physical tasks.

Physical Vitality

Indicate recovery from illness or inactivity, returning to a strong, vigorous condition.

Suggests someone is not only prepared but eager to engage in a competition or challenging activity.

Hints that a person or team has an advantage due to their readiness.

Can also refer to being psychologically ready or mentally tough.