Gatland says he has done some soul searching after Wales' miserable 2024 results.
He admitted that “there's no doubt that it was a challenge” because his job “is about performance and results.”
“There has been a fair amount of criticism which is completely understandable when you deal with professional rugby,” he added.
“You ask yourself and think about things you can do to improve and make a difference.
“It's also about trying to strike a balance between not making drastic changes and finding some tweaks to make things better.”
Gatland's second spell with Wales contrasts with his first 12 years at the helm, when the national team won three Grand Slam titles, four Six Nations titles and reached two World Cup semi-finals.
“It's also about looking at history and asking why we were so successful in the past, and what did you do that made those teams that won titles in the past so successful,” he added.
“It's about making sure you don't stray away from some of the philosophies that have made you successful with teams.
“Sometimes you can lose a little of that. You have to trust your instincts and your experiences.”
Gatland added: “I have overcome challenges. In the past when people have written us off and not expected us to do well, we have done exceptionally well.”
“I am proud of the achievements I have achieved in sport, whether it be during my time at the Wasps or with Wales or the British and Irish Lions.
He added: “Particularly in the World Cup finals, where there were four editions in which we did very well, in that we were unlucky not to go further than the semi-finals and perhaps reach the finals.”
Tierney said there would be a further review of Wales' progress after the Six Nations.
After announcing his team for the tournament, Gatland said that he did not have a set of results that needed to be achieved.
Gatland said: “I have never been set targets in the past, and there has never been a number set about having to win that number of games.”
“That's always the case. Everyone talks about it being a challenge, but we definitely need to show improvement.”
