When someone's described as 'In the Pink', that means he is in peak physical condition and in the best possible health.
Example of use: "Jon recovered from his surgery in less than 10 days, and is now in the pink of condition."
Interesting fact about In the Pink
The first recorded use of the phrase was in the 1597 play 'Romeo and Juliet' by Shakespeare: "I am the pinke of curtesie". However, at that time the meaning of the phrase was different, and it meant the very best example, the pinnacle, and didn't necessarily refer to health.
