Andy Ruiz Jr said he wants more than “15 minutes of fame” as he faced Anthony Joshua for the first time in the run up to their 7 December rematch.
The unified world heavyweight champion spoke in Saudi Arabia, where the fight will be held despite criticism over the country’s human rights record.
Promoter Eddie Hearn said boxing has at times been “narrow minded” over venues.
Ruiz, 29, has faced criticism over a loss of focus since beating Joshua but said he will “prove everybody wrong”.
The American – who fights under the Mexican flag – has shared videos and images of his improved lifestyle, including a new mansion and Rolls Royce.
He has also undertaken opportunities with countless talk shows and sponsors but said: “A lot of people are saying I am not training or taking it seriously. There are a lot of responsibilities to this.
“The hunger still remains. I don’t want it to be 15 minutes of fame. I want it to last, to be a generation, to be champion for more years.
“I am going to make history and win in the same fashion and the same way I did on 1 June and prove everybody wrong.”
Ruiz stopped Joshua in seven rounds in New York in June to land one of the biggest shocks in the history of heavyweight boxing.
Joshua, 29, lost for the first time in his career in New York and simply told those present in Diriyah that he was “humbled” by his welcome in Saudi Arabia and “looking forward to the challenge”.