Bent says he had to ditch White Hart Lane to salvage his confidence - and flagging England career.
He said: "It was horrible at Tottenham - people doubted me and my confidence took a battering. When you are not playing you're never going to make an impression."
Bent reached his lowest point in January this year when he missed at sitter in a 1-1 draw with Portsmouth - a chance Redknapp later claimed his wife Sandra would have tucked away.
The striker added: "It was a difficult period in my career, there were times I doubted myself.
"When people are levelling criticism at you it is not nice to take."