'You saw me out there and I was fresh. At my age it was becoming more and more difficult, which was one of the reasons I had to end it.'
Shearer now heads back to Blackburn tomorrow to secure the three points which will confirm Newcastle's place among Europe's elite next season.
Craig Bellamy is unlikely to partner him and may remain on the bench for the rest of the season after a furious touchline bust- up with Bobby Robson after the manager decided not to use him at all on Saturday.
The Wales international, who received his PFA Young Player of the Year award beforehand, was fit after a 10-game absence, but Robson kept faith with young striker Lomana Tresor Lua-Lua, who scored his second goal for the club.
Bellamy stormed off down the tunnel in the 78th minute when Robson, who had already replaced Greek defender Nikos Dabizas for Andy O'Brien, decided to send on midfielders Jermaine Jenas and Olivier Bernard for Laurent Robert and Nolberto Solano.
The Newcastle manager has made it clear he will not tolerate such behaviour from his players and Bellamy can expect to remain on the bench tomorrow night at least.
By the time Shearer was notching his second century, Lua-Lua had doubled Gary Speed's trademark header for the opener.
Charlton's toothless and fruitless attacks emphasise the urgent need for manager Alan Curbishley to deliver a few home truths to his squad this summer, as well as adding to it.
' When Shearer went through for the goal I didn't think he would miss,' said Curbishley. 'You just knew it was in and Alan Shearer and Newcastle have that desire. We didn't have it and we need to find it.'
