"It was a real privilege to be part of that," Thorn said.
"To be a European champion as well as winning the (2011) World Cup is incredible.
"I would have just been happy with all my NRL stuff and do some cool stuff over there.
"But I have always been a big dreamer.
"Years ago I never dreamed that what happened in my NRL career would happen.
"Now I just don't believe it again in union. To do and win all I have is amazing."
Thorn was only signed up on a short-term contract by Leinster in March because of an injury crisis.
Like most of his career, he came out a winner as Leinster collected the cup for a third time in four seasons.
Not that the former Brisbane Broncos and Crusaders star was ready to start discussing his retirement plans.
"Most of all I love the camaraderie," he said.
"As a six-year-old I used to get nervous before a game playing with my mates. Now, as a 37-year-old I still get nervous before a game with my mates. It's so special.
"It's not so much about what's going to happen next. It's just about enjoying today and only the Lord knows what will happen in the future. We shall see how it works out.
"Physically I have always been lucky. I feel pretty good. Mentally, that is the last thing I am thinking about!"
He has the chance to add another title next weekend.
Leinster will meet Ospreys in the final of the PRO12 competition in Dublin on Sunday.
"So I have to keep a little bit of an edge," Thorn said.
-AAP
