The 60-year-old Sunderland boss was able to breathe a little easier on Sunday evening after watching his side secure just a second league win in 19 attempts with a 3-1 victory at Fulham.
O'Neill, whose arrival at the Stadium of Light a fortnight or so short of a year ago sparked such joy, had found himself under mounting pressure after a poor run of results with some of his more disgruntled critics suggesting that the time might have come for him to go.
However, at the end of a week during which Chelsea counterpart Roberto di Matteo lost his job, O'Neill was able to look back on a difficult period with a wry smile as he prepared for Saturday's home clash with high-flying West Brom.
He said: "Somebody said to me, 'How come you don't put on any weight?', and I answered, 'I just worry for everyone'.
"It's no problem. You have to realise that during the course of the season, there are going to be periods where things are not going so well and you have to try to come out of them.
"There are other periods where you think you are going very well and looking forward to every single game that's coming up.
"You have to take a wee bit more balanced view of it. It's the season that counts ahead, it's where we end at the end of the season.
"Di Matteo has just lost his job - three and a half weeks ago, you would have said it was absolutely impossible.
"They won the Champions League, they won the FA Cup and they started off the season brilliantly.
"They were talking about a new style of play and a very inventive style of play. They had a bit of a hiccup along the way for a couple of matches or whatever the case may be and suddenly, a young man has lost his job."
Asked if he had slept a little more easily on Sunday evening, O'Neill said: "I'm not so sure that I have slept to well for 20-odd years."
However, O'Neill knows a much-improved display and result at Craven Cottage will count for little if it is not replicated on Wearside this week and beyond.
The Baggies will run out at the Stadium of Light perhaps having played their own part in Di Matteo's demise by beating Chelsea 2-1 at the Hawthorns last weekend, and the Sunderland manager knows the momentum created in south-west London could dissipate rapidly if his team falls back into its old ways.
He said: "It's important for us to go and build on this.
"There's no point in going down there and scoring some great goals, winning a game of football away from home, feeling terrific on the day of the game, the day after and maybe two days, and then finding out that you don't compete here.
"If we don't compete against West Bromwich Albion, we will be beaten."
Craig Gardner will be available again after serving a one-match ban, and with right-back Phil Bardsley now fit, there may be no need for him to fill in at the back as he has done for much of the campaign to date.
That will increase competition for places in midfield, where skipper Lee Cattermole turned in one of his better displays at Fulham and showed a commendable calm when he found himself on the wrong end of the two-footed tackle which cost Brede Hangeland a red card.
O'Neill said with a smile: "Usually when there's a challenge like that, Lee is the one who is being shown the red card, so that was quite pleasing that he came out of that and it went the other way. Even he was surprised.
"He was very good, very good. He is a good captain. He's very good in the dressing room with the players and for one still so very young, it's a commendable attribute."