The boss of Lloyds Banking Group has admitted he "overdid it" trying to turn around the bank before sleep problems eventually forced him into a temporary leave of absence.
Antonio Horta-Osorio said a specialist had told him his "battery was in effect so run down it was virtually on zero".
He went to the Priory clinic for a week to rest, he told a daily newspaper. The firm announced Mr Horta-Osorio would be returning to his job on January 9.
Recalling the time prior to being signed off work in late October, Mr Horta-Osorio said: "When I became chief executive in March I had a very clear idea of what had to be done. I threw myself into the job.
"There were very many issues to be tackled. I focused too much on too many details."
Mr Horta-Osorio said he was not going to work any less, just differently, by detaching himself from Lloyds' day-to-day running to focus on strategy.