"It's the same old tune, just being sung a little more loudly now," he said. "These type of things just help me lock in more."
Asked if there's any chance he won't be back, Bryant replied, "Not that I'm aware of."
James said, "When he comes back he's going to play at a high level."
Los Angeles signed the 35-year-old guard to a two-year, $48.5 million contract extension in November.
James, along with other NBA players, tweeted out well wishes to Bryant, although the two superstars hadn't talked until they shared a post-game hug.
"Especially games like today, you want to have the best guys out there," James said beforehand.
After the Achilles injury, Bryant expressed rare self-doubt. He hasn't felt any this time.
"The knee is not really a concern to me," he said. "The biggest question was would the Achilles respond to my game. It felt fine. It was strong."
Bryant was looking forward to playing against the defending NBA champions as a way to see where he was physically with his Achilles.
"This was a really big measuring stick," he said.
Instead, he sat at the end of the bench wearing a black suit and print T-shirt. He sat on a chair with extra inches of padding, likely to take stress off his left knee.
"My spirits are fine," he said. "I feel more locked in now than my entire career."