Billy Joe Saunders thanked Tyson Fury for putting him "back on the right track" after a difficult 2018.
In October, Saunders was denied a licence to defend his WBO middleweight title against Demetrius Andrade by the Massachusetts State Athletic Commission (MSAC) due to an adverse analytical finding in a Voluntary Anti-Doping Association test.
The 29-year-old relinquished his WBO middleweight title to challenge MSAC's decision due to the "mental anguish" caused by the case.
Saunders twice pulled out of fights against Martin Murray this year due to injuries and was fined £100,000 by the British Boxing Board of Control after a video uploaded to social media showed him in a car appearing to offer a woman drugs in return for performing a sex act on another passenger in the vehicle and assaulting a passer-by.
No drugs could be seen in the video and Saunders issued an apology, saying it was "banter" that went wrong.
Fury returned to the ring in June after two and a half years away from the sport while he battled depression. After beating Sefer Seferi and Francesco Pianeta, he was involved in a thrilling split-decision draw with WBC heavyweight champion Deontay Wilder on December 1.
Saunders thanked the former IBF, IBO, WBO and WBA heavyweight champion's influence ahead of his comeback bout against Zoltan Sera on the undercard for Josh Warrington's IBF featherweight title defence against Carl Frampton in Manchester next Saturday.
"This is a thank you message for Tyson. I've done a lot of bad things this year [that] I'm not proud of but I have to thank Tyson," said Saunders in a video posted on social media.
"I haven't boxed for a year for a reason, I was a bit down in the dumps.
"When I was going through that rough patch and acting a bit of an idiot, Tyson, who is probably the only man who can do it, put me in my place and had a good word and put me back on the right track.
"I was going down the wrong track. I have felt a little bit depressed all year and he's been through it so I have got to thank him for his help, because if it wasn't for him I would not be boxing next week."