The Santos forward has not played for his country since 2023 due to injuries and a knee operation that sidelined him for a year. Brazil coach Ancelotti has said Neymar has to be fully fit and playing well to be in contention for a World Cup spot.
"Physically, I feel great. I've been improving with every game," Neymar told reporters after Santos' 3-0 defeat by Coritiba on Sunday.
"I've done my absolute best - it wasn't easy. I'll admit it wasn't easy.
"It's been years of hard work, and also of a lot of nonsense being said about my condition and what I was doing. It’s really sad the way people talk about it.
"I worked hard, quietly, at home, suffering because of what people were saying, and it all worked out.
"I've made it to where I wanted to be in one piece. I’m happy with my performance, with everything I’ve done so far... Whatever happens, Ancelotti will certainly call up the 26 best players for this battle."
During Sunday's match, Neymar was involved in a furious protest after being wrongly substituted. The mix-up could not have come at a worse time for the 34-year-old, with Ancelotti set to announce his World Cup squad on Monday.
Brazil, looking to win a record-extending sixth World Cup title, will face Morocco, Haiti and Scotland in Group C of the June 11th to July 19th tournament in North America.