Full Idea
For the Stoics bodily health belongs in the 'indifferent [adiaphoron]' category: it does not matter if one is healthy. And yet, they created a subcategory of the 'preferable indifferent [adiaphoron proegmenon]', under which health falls.
Gist of Idea
Stoics said health is an 'indifferent', but they still considered it preferable
Source
report of Stoic school (fragments/reports [c.200 BCE]) by Peter E. Pormann - Medical Conceptions of Health pre-Renaissance p.45
Book Reference
Adamson,Peter: 'Health: a history', ed/tr. Adamson,Peter [OUP 2019], p.45
A Reaction
You have to be pretty tough to consider ill-health as an indifferent. The only good may be virtue, but the platonic tradition says virtue is a sort of mental health.