The 33-year old Australia international is gearing up for the 2012/13 campaign under new Victory coach Ange Postecoglou and after a disappointing season last term is looking to improve out of sight with the two-time champions.
"I feel very confident and the fittest and sharpest I've been in a long time and I think that's due to the fact that Ange has got us working very hard," Thompson said.
"From when he first took over to now you can see the difference just in terms of the football and certainly in the attitude of the players.
"Ange wants us to play a high intensity game and the guys are a lot fitter than what we've been in past seasons.
"I know I feel the best I've felt in such a long time - I feel like I'm 21 again...maybe 28! I feel as sharp as I did when I was 21."
Thompson and his Victory teammates will kick off the new campaign when they take on rivals Melbourne Heart at Etihad Stadium on October 5.