The former Sporting Lisbon star made his arrival at Old Trafford in 2007 but has struggled to make a regular impact, often finding himself on the fringes of Sir Alex Ferguson's starting XI.
But the 23-year-old believes that has changed this season after making 19 starts and four substitute appearances during his side's unsuccessful title retention bid.
And Nani says missing out on the Premier League crown on the final day of the season puts in him good stead to overcome the heartbreak by helping his Portugal team instead.
He said: "It was a pain not to win the Premier League with United but personally I am satisfied with the level of my season.
"I arrive like a player more mature and more experienced. Those could be important for my work with Portugal in the World Cup.
"The World Cup is not easy but we are obliged to improve our performance in comparison with the Euro 2008.
"I have much more morale and I am prepared for any challenge in South Africa. My dreams passed me by but it is important to be men in this team."
Nani's place in the Portugal first XI is by no means guaranteed, with the likes of Cristiano Ronaldo, Deco and Simao all vying for places on the flanks.
The United man hopes he can force his way into Carlos Queiroz's plans, though, and believes that the quality of his team extends beyond the realms of former Old Trafford team mate Ronaldo.
Queiroz's side face a difficult task in progressing to the knockout stages, with Brazil, North Korea and first Ivory Coast their opposition in Group G.
And Nani believes victory over Sven-Goran Eriksson's outfit will be crucial in the group's curtain raiser on June 15 at Port Elizabeth will prove vital in their hopes of making it to the last 16.
"I say that it will not be easy to obtain a fixed position in the starting eleven. Portugal is not only Cristiano Ronaldo and we have demonstrated this.
"Our first big final in the World Cup will be the very first day against Ivory Coast.
"That is key for us if we really believe that Portugal is able for a big competition in South Africa."