Sherwood's side were booed off at Villa Park on Saturday after a 1-0 home defeat by Stoke City left them third from bottom with four points from eight games.
Their only win was on the opening day of the season.
"I will use the international break to get my players fitter because they are not fit enough yet to play the way I want them to play," Sherwood said.
"For some of them it will be like a mini pre-season."
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Sherwood, who had half a season as Tottenham Hotspur manager in 2013-14 when Andre Vilas-Boas was sacked, took over the Villa job in February and endured a relegation battle with his side eventually finishing one place above the drop zone.
But with Villa selling the likes of striker Cristian Benteke to Liverpool and midfielder Fabian Delph to Manchester City, they already look like facing another season of struggle.
"I am very disappointed, we needed to win the game at home to a team that we could have leapfrogged," he said of the defeat by Stoke. "We failed to capitalise and it was not good enough.
"The situation is getting worse, it is alright saying ifs, buts and maybes, but we are not picking up the wins and that is why we are down near the bottom of the league."
Villa's next game is away at champions Chelsea on Oct. 17.
(Reporting by Martyn Herman, editing by Alan Baldwin)
