Natasha Jonas, the first woman to box for Great Britain at the Olympic Games, has retired 16 months before Rio 2016.
The Liverpudlian won bronze at the 2012 World Championships before reaching the quarter-finals at the London Olympics.
The 30-year-old, who hopes to move into coaching, told BBC Sport: "I don't think I've got the hunger and dedication to achieve any more.
"My mind is wandering to other things, and there's younger people coming through that want it a bit more."
Jonas took up boxing in 2005 to lose weight and rose through the amateur ranks before competing for Britain alongside gold medallist Nicola Adams and Savannah Marshall at London 2012.
|Who is Natasha Jonas?|
|Date of birth: 18 June 1984||Height: 1.72m (5ft 7in)|
|Birthplace: Liverpool||Olympic division: Lightweight|
|Did you know? Jonas had to drop down two weight divisions (8kg) for the Olympics as there is no welterweight category.|
She was favourite to win gold at the 2014 Commonwealth Games but lost to Australia's Shelley Watts in her opening fight after injuring her foot.
Jonas described not winning a medal at her home Olympics as the biggest regret of her career but said fighting there was her "wildest dream come true".
She added: "London 2012 will never be matched, it was surreal. I remember saying to my mum when I was four and watching the Olympics on the TV: 'Mum, mum, I'm gonna be there.'
"It took me 24 years but I still achieved it."
Jonas is an ambassador for women's boxing, which has seen a 56% rise in the number of people taking up the sport in England since the 2012 Games.
And she welcomed the "phenomenal" changes she has witnessed.
Jonas said: "The women's England Boxing Elite Finals will be held as the same event as the men's - that's big progression.
"The number of rounds you have to compete in at tournaments to become champion has increased. When I first started, I was boxing twice to become champion and now you're boxing four or five times.
"You've got the seniors, the youths, the juniors, and that wasn't there before. If you wanted to box, you had to box whoever."
Jonas is also proud of Britain's development into a force in international women's boxing.
She said: "Britain has surpassed other countries that have been doing it longer than us.
"We used to go to tournaments and we'd be lucky to reach the second round. Now we're coming away with medals."
Jessica Creighton analysis
"The was an air of ease about Natasha when I spoke to her at her home boxing club, the famous Rotunda ABC in Liverpool. She seemed happy with her decision and excited for the next chapter in her life.
"She described boxing as 'extremely tough' and spoke with honesty about not having the motivation to carry on, particularly with the foot injury she picked up at the 2014 Commonwealth Games.
"Natasha is a pioneer in the sport and an inspiration to many."