Cook made a blunder against Hull that led to a goal and in the defeat to Arsenal last week he gifted the ball to Alexis Sanchez who slotted home for the Gunners.
Cook knows if he is to progress he must cut out individual errors – starting on Sunday in the high-profile visit of Liverpool.
“I’m only 25 but I’m taking on a role I need to embrace and enjoy, but at the same eradicate mistakes to take my game to the next level,” he told reporters.
“That’s why Sunday hurt me so much. It shouldn’t happen, so that’s something that has to change.
“As a footballer it’s the worst possible thing that could happen. It’s difficult to talk about, because emotions change throughout the game
“I’ve put Sunday behind me but I wouldn’t be able to describe the emotions in my head at that point. I wouldn’t want to compare it to normal life.”
Colchester will hand late fitness tests to Ryan Jackson and Brandon Comley prior to their clash with Yeovil.
Arsenal secured their place in the quarter-finals of the Europa League following their 3-1 defeat of AC Milan at the Emirates Stadium on Thursday.
Danny Welbeck scored twice against AC Milan to toast his England recall by sending Arsenal into the last eight of the Europa League.
Ipswich striker Joe Garner will not play again this season after it emerged he suffered a fractured skull against Sheffield United last week.