Cuellar believes that the Black Cats, who narrowly escaped relegation from the Premier League last season, will be in better shape come the business end of the 2013-14 campaign.
Carlos Cuellar: "The way we'll approach this pre-season, I think it will make us a lot stronger physically.
"In the last few games of last season, you could see the players pick up little injuries or cramp because we were working so hard to win every match.
"Sometimes, you give more than 100%, and we didn't have that extra fitness we needed. I don't think we're going to have that problem next year."
SUNDERLAND FIXTURES:
Saturday August 17
15:00Premier League Sunderland v Fulham
Saturday August 24
15:00Premier League Southampton v Sunderland
Saturday August 31
15:00Premier League Crystal Palace v Sunderland
Saturday September 14
15:00Premier League Sunderland v Arsenal
Saturday September 21
15:00Premier League West Brom v Sunderland
Saturday September 28
15:00Premier League Sunderland v Liverpool
Saturday October 5
15:00Premier League Sunderland v Man Utd
Saturday October 19
15:00Premier League Swansea City v Sunderland
Saturday October 26
15:00Premier League Sunderland v Newcastle United