The Black Cats lie 15th, just four points above the relegation zone, and are without a win in seven matches following last Sunday's 1-1 draw at home with 10-man Norwich.
Things appear little better off the field with the club this week posting losses of £27 million for the last financial year, but O'Neill is remaining positive.
“Things have not gone our way recently but we are certainly not looking for excuses,” O'Neill told The Daily Mirror.
“We are simply looking to get on with the job of producing the results we want.
“When you have not won for a while, pressure to win the next game gathers momentum but that is part of football. Maintaining self-belief is essential.”
Sunderland face Manchester United and Chelsea in their next two games, followed by their North-East rivals Newcastle United.