The actress, who will be seen leaving Weatherfield in the coming weeks, told TV Times that the demands of being a regular on such a high-profile soap left her feeling exhausted and concerned for her health.
"Coronation Street is relentless," she explained. "For years I've put the job before everything. It's the only way to survive in that programme, but I'd put the job before my health and I can't do that anymore."
Callard has previously spoken out about suffering from depression and said that the treatment she receives for the condition had motivated her to make the decision to leave the cobbles after two decades.
"I'm still on medication and I just need some time for me. It wouldn't be fair to keep on working and make a commitment I couldn't keep," she commented.
The 54-year-old also revealed that her last scenes were particularly emotional.
Callard said: "At one point, the make-up artist, Jane, was shouting at me from behind the set, trying to be harsh with me to stop me crying."
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