After facing Spain, the Manchester United left-back withdrew from two of the next three squads through injury and was not picked by England manager Gareth Southgate between March 2019 and this month.
“I’ve a few massive regrets and I couldn’t stop thinking of the mistakes that I made in the past, especially with England,” Shaw said.
“I pulled out of a lot of camps. Around that time, I was maybe not in the best condition but I think over the last two years I’ve thought about it so much – that was my biggest regret.
“And, of course, letting Gareth down. I tried to keep in touch with him just to let him know that things had changed. He’s said he’s picked me on merit and how I’ve been performing.
“The past is the past and hopefully we’ve forgotten about that now and can just focus on the future and I want to keep impressing him.
“The last time I played was [against] Spain. Of course, I wasn’t playing for my club much then and it showed that he [Southgate] still very much trusted me because he played me in that massive game.
“In the camps after, my biggest regrets were just pulling out [and] how I pulled out. Maybe at the time, mentally I wasn’t right. Like I said, I massively regretted it.
“Playing for your country is a massive privilege and an honour and I think at times I took that for granted,” Shaw added.
“You watch the World Cup, you watch how good they were doing and you can see how good the squad’s becoming and I wanted to get back involved with England. Who wouldn’t?
“I’m just really privileged to be able to get another chance and hopefully stay in the squad for more games to come.
“I just want to forget the mistakes I’ve made in the past and Gareth’s done that so we’re just focusing on the future and obviously what’s happening now.”
Shaw was dogged by injuries after joining United in 2014 and faced a barrage of public criticism from former manager Jose Mourinho.
Asked about his reasons for withdrawing from the squads in October 2018 and March 2019, Shaw said: “I did have problems at the time, as in injuries but maybe they were ones that could have been sort of dealt with but there was a lot on my mind, especially in times I had at United.
“People obviously know what was going on but Gareth has given me another chance and I need to prove to him that, of course I’m different and I want to be part of this squad.”
Shaw admitted there were times when he feared his England career was over but says he learned of his recall over a week before the latest squad was announced following a tip off from United boss Ole Gunnar Solskjaer.
“At times, yeah there was [doubt that I would play for England again],” he said. “Especially my family.
“We had a few discussions and we thought that maybe I wouldn’t be able to get back into it but deep down I always believed that I could and I worked hard.
“I’m so happy to be back. I knew [about my recall] quite a bit before because Ole had spoken to Gareth, and I think Ole was really happy for me so he told me really early.
“I knew maybe a week before, but I kept it very quiet I only told my girlfriend, just because I didn’t want to tell too many people, I just wanted to keep it quiet and wait until that Thursday came and I’ve got the text and then I could tell my mum and dad.
“Only my girlfriend knew but I told my mum and dad earlier in the morning on Thursday.
“I did really want to tell them that but I had to wait and I think at the time there were some quite important games coming up for United so I think my focus was fully on that.”