In this story the world is known that there is magic and many can do things though few can do more than the equivalent of creating a spark before getting tired. Having many ways to channel the mana some are atunned to specific types of magic and even without practice the tallented have talles that the trained eye can see. For the healers I thought it would be fun to have them be very muscular people due tho their subconscious applying their gifts in self healing. Not body builder size muscle but very much noticeable.
The healing is not Wolverine level healing but close. It would take a day for these people to grow a missing limb (though without training they lack the mana) but the point is for what muscles fibers are concerned the process is very fast.
Would it be possible that with a "normal" daily routine for a beyond medieval society someone with super healing build up noticeable muscle? I would assume the farmer or the wood chopper and the hunters would but what about the mushroom collector or the basket weaver?