Wayne Rooney said he was "embarrassed" towards the end of his time at Manchester United because of a lack of opportunities.
Rooney, the all-time leading goalscorer for both United and England, featured in 39 of the Red Devils' 64 matches in 2016-17 - his last season at the club.
"There are moments when you do doubt yourself," he told Sky Sports.
"I believe I was good enough to get back in the team, but I never really got that opportunity."
Rooney, who left United to rejoin Everton and then moved to MLS club DC United, was speaking before his farewell game for England against USA on Thursday.
The 33-year-old added: "I came on for one minute in the Europa League final. I was about to come on against Southampton in the League Cup final, and in those moments it was embarrassing.
"It was getting to a point where I was embarrassed. I thought 'I can't keep doing this', as hard as it was to leave United.
"In the Southampton game, [manager Jose] Mourinho came to me and said: 'I want you to lift the trophy.' I was like: 'Well, I didn't even play in the game.'
"He was persistent with it, and I literally lifted it and moved it on. What was I doing? I need to move on and go somewhere else."