The defending NBA champions beat the Clippers at the Staples Center for the first time since 2007, clinching a 116-112 win.
The forward told reporters: "Obviously we've had our battles with [Clippers coach] Doc [Rivers], being in the Eastern Conference for so long, so we know how well his team is going to be prepared.
"I think it was just our mental toughness, especially in the third quarter when they made their run. We just stayed composed and found a way to get a win. We made stops and executed offensively."
James finished the game with 31 points.