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In Wayne Bennett's first competitive game in charge, England were pipped by one point to fall to defeat at Huddersfield's John Smith's Stadium.
The 17-16 loss, along with Australia's win over Scotland put hopes of reaching the final in doubt, although there are still two matches to play.
"It's only the first game of the tournament," the 28-year-old said.
"If we dwell on the bad things we won't do very well. We have to look at the positives, we have the right man in charge [in Bennett].
"This will take a day or two to get over, we have to focus, we did a lot of good things and we need to take that into next week."
One positive of Saturday's loss was the continuation of the Leeds Rhinos man's terrific scoring record, crossing for his 29th international try in 29 games.
Hall has the opportunity to take his tally to 30, five more than Sam Tomkins and extend his lead as the top scorer in England Test history.
"Its bittersweet," Hall added to BBC Sport. "It was a great assist from Gareth Widdop, but ultimately the bigger picture stuff, that we lost the game is hard to take.
"It's fine margins, that's Test match rugby and the most disappointing thing is that we had enough to win the game."
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England must take the positives from Saturday's Four Nations opener defeat by New Zealand, says winger Ryan Hall.