The Frenchman, who took over in September, saw his team move out of the Barclays Premier League relegation zone with a 1-0 win over Manchester City. And, with one defeat in five games ahead of Tuesday's match against Wigan, Houllier admits his camp is a lot happier than the last time they faced City.
He explained: "You can't prepare for a game if someone is pulling a face - it drains the energy. And there was a time when the players playing were moaning and whining. We probably have the best job in the world so when you see unhappy people not doing basic things, like being focused and ready, you get angry."
Houllier is pleased with his team's improvement since the turn of the year, adding: "We were probably at our lowest when we played there.
"But in five games since the start of year, we've won two, one away in the FA Cup and one against Manchester City, who are one of the best sides.
"We've drawn two, at Chelsea and Birmingham, coming from behind. I think a couple of months ago it would have been the other way around.
"We have lost to Sunderland, when we were down to 10 men.
"The team is physically and mentally stronger - that is an important aspect. There's a major change there.
"But we have to stay humble. Players must combine ambition and humility - that's the cocktail to win."
Source: PA
Source: PA