Pepe declared Portugal have the quality to become world champions but admitted he was uncertain about his own prospects of playing at Qatar 2022.
Fernando Santos' team clinched their place at the finals with a 2-0 play-off win over North Macedonia in Porto on Tuesday.
Bruno Fernandes got both of the goals for the Euro 2016 champions, who beat Turkey in their previous play-off match.
It means Cristiano Ronaldo is set to feature at a record-equalling fifth World Cup, though fellow veteran campaigner Pepe is not quite so sure of his place.
While that does not seem likely to be down to coach Santos, with 39-year-old Pepe still a mainstay of his defence, the former Real Madrid centre-back insisted that now his focus is on helping Porto, rather than thinking about the showpiece that starts in November.
"I still don't know, there's still a lot of time," Pepe told reporters.
"Now I have to focus on my club's games. I didn't want to mix things up, but I know that at this age I have to think game by game. Obviously I want to help Portugal.
"I'm very happy to do what I like to do, play football, I try to pass on this desire of mine to enjoy every second and moment in football, because it passes very fast. I am 39, but I still have the same illusion of a kid of 15, 18, 20 years old. I try to make [my team-mates] feel this happiness because we are privileged."
Pepe played a crucial role in Portugal's second goal against North Macedonia, making a fine tackle deep in his own half to start the counter-attack that resulted in Fernandes steering home Diogo Jota's cross.
Portugal were ultimately comfortable winners, having 11 attempts and restricting their opponents to just three going the other way, with none of those hitting the target.
Yet the fact they were even in this play-off in the first place, and could well have been facing European champions Italy if not for North Macedonia's shock win over the Azzurri last week, points to a sense of underachievement.
Pepe, though, feels Portugal have all the tools to succeed in Qatar.
"We have a lot of quality, we know that for this feat we have to work hard and be very strong mentally, be a humble and warrior team, which we were many times in the period in which we won the Euros and the Nations League," he said.
"We have players with a big future, who play in big clubs in Europe. I believe we have the capacity to be world champions, but we'll take it easy, prepare well, so we can be at our level.
"It was an emotional night, the atmosphere in the stadium was fantastic, we felt that positive energy from everyone. I feel privileged to be part of this group, to be able to live this wonderful night.
"It [would be] a huge injustice not to be at the World Cup, the way we work, the way we dedicate ourselves, the criticism we receive. We proved to be a humble team."