(CNN)Cesare Prandelli has stepped down from his position as head coach of Serie A side Fiorentina, saying that a "dark cloud" has developed inside of him.
In a moving open letter published on the club's website, the 63-year-old explained that he has been experiencing "a period of profound distress which is preventing me from being who I really am."
Prandelli returned to coach Fiorentina for a second time in November 2020, 10 years after leaving the club to manage the Italian national team following a successful five-year spell with the Serie A team. However, La Viola has been struggling this season, with the club sitting in 14th place, seven points above the relegation zone.
"This is the second time I've left Fiorentina," he wrote. "The first time was not my decision, but this time it is. In life, as well as the good times, there are also dark moments which can get on top of you.
"I have been going through a period of profound distress which is preventing me from being who I really am. I began this experience with joy and love, spurred on by the enthusiasm of the new owners.
"It's likely that that my love for the city, and the memories of the great moments I've experienced here, made me blind to the early signs that something wasn't right inside.
"My decision has been guided by the enormous responsibility I have towards the players, the club and -- last but certainly not least -- to the Fiorentina fans, for whom I have great respect," he added.
"All players at this level have talent, and when you have talent you are perceptive -- I wouldn't want my distress to be picked up and affect the team's performances."
During Prandelli's first spell in charge at the club, he guided Fiorentina into the Champions League on two separate occasions. His success saw him hired as the national team head coach, where he stayed for four years until resigning following a disappointing 2014 World Cup in which Italy exited at the group stage.
'Rediscover my true self'
Prandelli's other previous coaching roles include Roma, Galatasaray and Valencia, but he hinted that this could be his last job in management. Prandelli left Roma in 2004 after only a short time in charge to care for his sick wife, who later passed away.
Fiorentina said it accepted Prandelli's resignation "with great sadness" and has confirmed that Beppe Iachini has been placed in charge of the first team.
"Over the past few months, a dark cloud has developed inside of me, changing the way I see things," Prandelli said. "I came here to give 100%, but I now feel that this is no longer possible and therefore I have decided to step back for the good of everyone involved.
"I'd like to thank Rocco Commisso and his wonderful family, Joe Barone and Daniele Prade, who have always been right behind the team and me. Most of all, though, I want to thank the people of Florence, who I know will understand.
"I'm aware that this could be the end of my career as a coach, but I have no regrets and don't wish to have any. The world I've been a part of for my whole life probably isn't right for me anymore -- I no longer see myself in it.
"I've certainly changed, but the world is moving faster than I thought too. That's why I believe the time has come for me to stop being swept along, stop for a while and rediscover my true self once again."