Willie Aitchison says his side needs to learn quickly and cut out the errors which cost the Methil men at Glebe Park on Saturday.
The Fifers lost two late goals at Brechin to lose their second league game on the trot.
The manager concedes that sides will punish the Fifers for these errors, so wants to see a tightening up at the back of the park.
“I’m frustrated with the way we lost the first goal because we had done OK up until then,” he said.
“If they’d scored a really good goal that they’d created from their own half, or from a set-piece, then that’s one thing, but it was a mistake that has cost us the goal.
“We caused our own downfall because they punished that mistake.”
However, the manager said that team spirit remains strong at Bayview and the side got the defeat out of their system with a good session on Monday.
East Fife have had a tough start to the season, with a cup tie against Championship side Morton and a league opener against recently-relegated Dunfermline among their opening fixtures.
“The boys aren’t lacking in confidence,” said the Bayview boss.
“We had a good training session and the banter was back and flowing again.”
Skipper Craig Johnstone was taken off during Saturday’s loss at Brechin but did take part in training on Monday.
‘Keeper Greg Paterson has been added to the ranks, with the manager saying he expects him to push Michael Andrews hard for the number one jersey.
“If Michael doesn’t perform to the standards we expect, then I’ll have no problem at all playing Greg,” said the boss.
Christian Nade is expected to start ball work with the side in the next week.
This week, the Fifers welcome Arbroath to Bayview.