Carra said: "Even when you win there is always something about the performance you're not happy with. I'm already a bit like that as a player. If I have an average game or I make a mistake it's on my mind until the next game.
"It sounds stupid because I love playing football, but sometimes I can't wait until I'm finished so I won't have all the ups and downs any more.
"When I gave the last-minute penalty away against West Ham recently and we lost the game, I didn't sleep properly until after our next game. I think, 'Do I really want this?'
"It's important to me that I enjoy what I do - and I'm not sure you can as a manager!"