Mark Aston’s side picked up their first win since Round two against fellow strugglers Oldham last weekend, which Knowles believes will provide a huge boost ahead of their clash against Widnes Vikings on Sunday.
Speaking on Monday, he said: "Going into training tomorrow the morale will be twice what it has been.
"It was a good result, a much-needed one. It was a couple of desperate teams, we needed that to get back to playing with some confidence.”
Sheffield had lost four of their previous six matches, with Aston criticising the team for a drop in standards following their impressive start to the 2021 season.
They took two wins and a draw from their first four fixtures.
Knowles, 27, who has been ruled out for up to 12 weeks after damaging his vertebrae, admitted team spirit had been hit hard by the poor run.
"It's been negative, people haven't wanted to be there. We have been doing a lot of hard work because of the losses,” he said.
"People were getting a bit despondent, a bit negative and a bit moaney at each other, me being one of them.
"We needed to learn that losses are going to come but it's how you deal with them.”
A top-six spot would see Sheffield qualify for the play-offs this year. They are currently two points off sixth place in eighth.
“If we can get a couple of wins behind us we can kick on,” said Knowles. “The top six places aren't too far away, we can aim for that as a minimum.
“We have got the personnel to do it but we need the mindset and people willing to do the hard work.”
Sunday’s opponents are one place and one point below them in the league table. There will be no room for complacency, however, Knowles said.
“We have had a couple of winnable games but we haven't won them,” he added.
“Widnes are a good team, they have some experienced players in there and some young ones that want to impress,.”
Front row Scott Wheeldon will be unavailable for Sheffield’s next three matches after he was suspended for dangerous contact.