Kearney started his first match on the tour in Tuesday's 14-12 defeat at Canberra Stadium in a makeshift backline that failed to breach the dogged Brumbies defence for a single try.
"Most of the guys who were playing are disappointed, but it is important that we realise there is a bigger picture, which is Saturday and the three-Test series," the 27-year-old Irishman told the Lions website.
"We need to get back on our feet pretty quickly.
"We will slowly realise that this is one set-back, it is not what the tour is going to be remembered for. If the 23 guys can get us back to winning ways on Saturday then tonight will be a distant memory.
"It won't affect the team mentally. This week is all about Saturday and it still is. It would have been nicer if we had won and it would have given us greater momentum and there would have been a real high spirit within the camp, but I don't think it will affect us hugely."
The loss ended the Lions' unbeaten run of five matches this tour and was their first loss to a provincial side since being upset by Northern Transvaal in South Africa in 1997, their last victorious tour.
It was also the first win by an Australian provincial side over the Lions in more than 40 years.
Coach Warren Gatland described the loss by the Lions' weakest side on the tour as a 'wake-up call' but Kearney denied the squad had needed to be shaken out of a sense of security.
"You only get timely wake up calls if you deserve or need them and I think it would be a bit unfair to say we needed one," Kearney, on his second Lions tour, added.
"There were a lot of guys out there playing for the first time and it was a team that was put together over only the last few days.
"There were a lot of things that we should have done better, things that should be a given as professional rugby players. They were the things that we came up short of and that will be the most disappointing."
Former Wales winger Shane Williams, one of three backline players flown over just before the tour match, conceded it was a big ask to slot in to the line-up late.
"I had one team run yesterday. Obviously it is never easy to fit back in and I had to get used to the calls and patterns but I'm not using that as an excuse," said the 36-year-old, who was called in by team management just for the Brumbies match.
"We trained hard, did our homework and had a look at the Brumbies, our calls and moves but as I said it just wasn't meant to be."
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