It was recently reported that the X Factor USA judge struggled to juggle his many television commitments and personal life problems, leading to some form of a collapse.
His former partner and good friend Sinitta explained that the breakdown was a good thing for Cowell, as it has made him slow down.
"He did have a tough summer but he's turned it all around," she told The Sun.
"It was a good wake-up call because it's made him try to bring harmony to his whole life, balancing the work and pleasure thing instead of being a complete workaholic."
Cowell was reportedly placed on a strict detox programme in order for him to recover from the breakdown, and was confined to bed for a week.
Sinitta also spoke about X Factor guest judge Geri Halliwell, and backed her for a future permanent role.
She said: "I love Geri. I think she's absolutely insane but now that we don't have Simon, we need someone to take the crazy role."
Simon Cowell recently tipped One Direction singers Louis Tomlinson and Harry Styles for future X Factor roles.