Keegan watched as Newcastle overpowered Stoke 4-1 and his first match in charge will be Saturday's home clash with Bolton in the Premier League.
"I am just as excited this time as I was when I came to play here at 31 and when I came as a manager at 43 or 44," he said.
"I think this is right, I have certainly inherited a strong, talented group of players - which is something I didn't have when I came last time.
"When I came last time we were wondering whether we could fill the stadium. That is not a problem.
"They will be trying to get a stadium big enough if we can put some football on and get some success here.
"The job in hand is a big job, it is a great club."