Carl Froch insists his desire has not diminished and he still loves the intense training needed to become "superhuman" for world title fights.
The Nottingham boxer, 35, is fighting American Yusaf Mack in a first defence of his IBF super-middleweight world title in his home city on 17 November.
He told BBC East Midlands Today: "Most of the time, when I'm not training, I'm in normal shape because I'm only human.
"But then I go from being from human to superhuman and I love the transition."
Froch added: "I love watching my body shape change and becoming this 12 stone, lean, mean fighting machine. It is all geared towards one night and it is not long away now.
"It's the desire that gets me out of bed in the morning and gets me on the long, cold and dark runs.
"That desire keeps driving me and, as long as I have got that and still enjoy it, then I will keep going and keep fighting."
Mack has a record of 31 wins, two draws and four defeats, including an unsuccessful challenge last June for Tavoris Cloud's IBF light-heavyweight title.
Froch became a three-time world champion when he beat Lucian Bute in May and faces a rematch in March.
But before then he insists his American opponent will provide a stern test.
"People say it's an easy fight, but there is no such thing as an easy fight," Froch said.
"He is ranked five in the world and he has only been beaten a couple of times. He will do what he needs to do and try it on.
"Anything can happen. It could be messy so I need to be 100% focused and dedicated and a consummate professional.
"Potentially it's an easy fight compared to who I have been fighting, but this will be a tough fight and I need to be on my 'A' game."
Froch, who turned professional in March 2002, says his training has gone according to plan.
And he insists he is completely ready - despite saying he has one or two injury niggles.
He said: "It's a 10 to 12 week camp watching my diet and nutrition, getting myself physically prepared, getting my strength and conditioning correct and it's all geared towards that one day.
"I am battle-hardened and this will be my ninth world title fight on the spin.
"I have been boxing since I was 10 years old so have been boxing for 25 years. I am a seasoned professional. I am well-established physically and mentally to where I need to be."
But Froch says the level of competition at which he has consistently fought since winning his first world title in 2008 means he can never relax.
"It doesn't get easier, it gets harder," Froch said.
"You become fitter and stronger but the opponents get harder and harder. When I first turned professional I was fighting journeymen and warm-up fights to get to this level.
"My first title was the English title, then the British title and Commonwealth title and then you step to European level, and then you box for a world title.
"A lot of people became world champion and have hand-picked easy defences. I boxed my mandatory fights and whoever wants to fight me, which is always top level."