Sam Allardyce's charges have slipped to 17th in the Premier League table, and only sit outside the relegation zone by virtue of goal difference.
The Upton Park outfit have only registered three victories in England's top flight this season, and were completely overrun by a rampant Liverpool side in a 4-1 defeat at Anfield on Saturday.
That setback followed a disappointing performance in a 1-0 defeat at Crystal Palace on Tuesday, and Allardyce will be ruing his side's inability to build on the 3-0 triumph over Fulham on November 30.
But Jarvis believes the side cannot hide away from their precarious position, and must fight their way out of trouble - starting with Saturday's encounter with bottom-placed Sunderland.
"We can't feel sorry for ourselves," he told the club's official website. "We need to stay positive and make sure we are working extremely hard as we did at Liverpool and get that positive result we need to kick-start our season.
"It's definitely time to roll our sleeves up and fight. That's exactly what we need to do. However we get the three points, it doesn't matter what we do, we just have to get them and get ourselves up the league.
"We will try to do exactly what we did against Fulham when we face Sunderland on Saturday. If we do, then we'll get three much-needed points and hopefully we can do that on home turf."
