DeGale will make the fourth defence of his IBF super-middleweight championship - and his first on home soil in three years - when he takes on America's Truax at London's Copper Box Arena on Saturday.
The fight is also DeGale's first since surgery on his right shoulder following his bruising draw against Badou Jack in January.
But the 31-year-old, who also had a bridge replaced after his two front teeth were knocked out by Jack, reckons he is in as good a condition as when he beat Andre Dirrell to become world champion back in 2015.
"It has been a good couple of years since I have felt as healthy as this," De Gale said. "Probably since before the Dirrell fight when I won my world title.
"As soon as I had the operation on my shoulder in June I was straight back into the gym, doing my physio and building my strength up. I could run after a couple of months following the fight, so my fitness was there, but it was just about getting back, and starting to punch and spar.
"The road has been frustrating. I could not lift my arm, and all I could do were slight movements and routines, so it was annoying. But I am in good shape. My shoulder has healed well. It is nice and strong and I can't wait to box again in London."
After defeating Dirrell in Boston, DeGale won on points against Lucian Bute in Quebec and Rogellio Medina in Washington before his controversial draw with Jack in Brooklyn.
DeGale's compatriot Anthony Joshua saw off Wladimir Klitschko in a mega fight at Wembley earlier this year before defending his title with a 10th-round stoppage against Carlos Takam in Cardiff.
Joshua is the odds-on favourite to be crowned BBC Sports Personality of the Year later this month, but DeGale - Britain's first Olympic gold medallist to win a world title - insists he is not the country's forgotten man despite his fights overseas and 11-month spell away from the spotlight.
"A lot of people have called for me to come back here and I don't think I was forgotten when I boxed away," De Gale added. "If anything it made me more exclusive.
"It feels good to be back and I can't wait to box in front of my own people and fans who could not afford to watch me fight abroad."
Looking ahead to next week's SPOTY Awards, DeGale added: "It would be a fantastic thing for boxing if Anthony Joshua won Sports Personality of the Year, but will he win it? I doubt it.
"His time will come, but I don't think it will be this year as he has got a lot more to achieve before he wins SPOTY."
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