The men from the Emerald Island kicked-off their campaign in perfect fashion with an away win over Wales but crashed to defeat at home against England.
England are in the driving seat, with two wins from two, but O'Brien remains positive over Ireland's Championship prospects.
"There's still a lot to play for. The Six Nations is and it isn't out of our own hands.
"If we leave ourselves in the best possible shape, there will be a slip-up somewhere for the other teams down the line.
"Anyone can beat anyone on any day. If we leave ourselves in the best possible position, we can do no more than that."
Ireland will be without Cian Healy for the clash against Scotland, following his ban for stamping.
Jonathan Sexton and Mike McCarthy have also been ruled out due to injuries
But O'Brien, Brian O'Driscoll, Rob Kearney and Donnacha Ryan are all expected to recover from various bumps and bruises to face Scotland.
And the fierce ball-carrier is relishing get back into action at Murrayfield.
"We're looking forward to getting back on the horse against Scotland. It's a good game for both teams," said O'Brien.
"Our errors, as a team and as individuals, stand out from the England game. They cost us.
"A few of them happened within minutes of each other and put us under a bit of pressure and they kicked a couple of scores from that."