Gatland is currently preparing for Wales' first warm-up game against England at Twickenham on Saturday, with two more fixtures to follow before the tournament.
England will travel to the Millennium Stadium one week after the Twickenham clash and Wales will then face Argentina at home on August 20.
While the big three southern hemisphere team will go into the tournament off the back of a full Super Rugby season and Tri-Nations competition, Gatland hopes his side's fitness work will also stand them in good stead.
"The southern hemisphere teams will probably be a little bit better prepared, in terms of the game time that they will have had together," Gatland said.
"But hopefully we've got the physical preparation done as well in terms of having what is almost like a pre-season - we've had a little bit of a break and we've been able to do the work in the gym.
"(There has been) some quality time spent together as well, which you don't usually get."
But centre Jamie Roberts says that all the work in the gym will count for nothing if Wales, who finished fourth in this year's Six Nations table, cannot produce the goods when it matters.
"We all know that on the pitch is where it counts," Roberts told Sky Sports News.
"You can train as hard as you like but all of us as individuals, and collectively as a team, need to show what we can do on the pitch.
"There's no point being the fittest guys in the world if we're not good rugby players, we are well aware of that."
Gilbert has released a new line of rugby cleats. The Gilbert Virtuo 8S is part of the exciting new product. Check it out.
The entire All Blacks apparel line has been updated for 2013/14. Check out the New Zealand All Blacks polo.
The Nike Tiempo is a solid rugby cleat and one of few styles still made from full-grain natural leather.
The Gilbert Blitz 8S rugby cleat is a great cleat at a great price of $69.99. Get a new pair of cleats today.
A cool looking all black rugby cleat with the high performance adidas is known for. Get in the Gear!
Wear the crest of the British and Irish Lions on your t-shirt. A great look for the summer.
$29.99
The All Blacks Performance t-shirt is black with hints of blue from the training jersey. Very Cool.
The New Zealand All Blacks training jersey for 2013/14. Get in the Gear!
The USA Rugby Pro Alternate rugby jersey is perfect for any fan of the Eagles. Get yours to wear during the summer Test matches.
The NEW All Blacks 2013/14 jersey has arrived at World Rugby Shop. Dare to wear the colors of the All Blacks.