"I am getting older," said the 33-year-old. "That is fairly obvious.
"But I am still as enthusiastic as I have ever been and I am excited about the challenge this season presents.
"Every season, I just try to look for that extra five or 10% that will keep me involved, whether it is in my preparation for games, or what I do afterwards with the use of ice baths and things like that.
"This year, I am not playing international football, which will give me a chance to get some rest.
"Hopefully then I can come back refreshed and it will help me towards the end of the season when games start to come thick and fast."
United boss Sir Alex Ferguson has reinforced a championship-winning squad with mouthwatering talent in the form of Owen Hargreaves, Nani, Anderson and Carlos Tevez, whose long-awaited arrival has finally been confirmed.
None of the new boys are expected to start today against Reading but Giggs is confident when the £60million quartet are involved, they will make an immediate impact.
"When you sign new players, especially exciting attack-minded players like the ones we have, it excites players and staff, as well as the fans," he said.
"There has to be a settling-in period but they have looked good in training and in games, so I wouldn't be surprised if they hit the floor running."