Fury stunned Klitschko in Dusseldorf last November, the Briton winning a unanimous points decision to claim the WBA, WBO and IBF heavyweight belts.
A rematch clause was duly activated by Klitschko and the duo are due to meet again in Manchester on July 9.
Yet Fury is adamant the bout will be his last.
The controversial 27-year-old revealed his intention to retire via his official Twitter account on Sunday.
“I set off today for what promises to be a very hard 8 weeks training camp, this will be my best fight, then I’ll retire 100%,” wrote Fury, who subsequently outlined a desire to spend more time with his family.
In an interview with iFL TV, he said: “I’m so sick of it [boxing]. I’ve got no motivation to carry on.”