Vea joined Saints from London at the end of 2014.
The forward had two seasons at Langtree Park, the second was plagued by injury. He has joined Leigh for 2017.
Vea said the end of his time at St Helens was a “natural conclusion”.
“I mean when you get injuries and that, because I’ve been through this my whole career with injuries, and when you come through that you start ‘umming and ahhing’,” he told Love Rugby League.
“I mean when I got there there was nothing holding me back so I got there full steam ahead.
“I was ready and raring to go and there was no doubt in my mind and I think that showed in how I started the season there.
“And then come that injury time when you start doubting your abilities and stuff like that and you don’t have time to kind of have that mentality.
“You know what the leagues like, everything is results based and performance based so I think I shot myself in the foot with that struggle but at the end of it I took a lot out of it as well.
“It was just a mutual thing and like I said when I went there, St Helens are known for winning things and I wanted to win things and be a part of that, which didn’t happen for me.
“But I think I got a lot more out of it than I thought I would.
“It’s all good to get all the trophies and all that, but I feel like I’ve come away from it a lot more wiser.”
Vea has signed a two-year with the Centurions.
Asked if he could see finished his career off at Leigh, the back-rower admits he hasn’t given it any thought.
“To be honest I’ve never really had to think that far ahead with my rugby league career,” the 29-year old said.
“I still can’t believe I’m playing to be honest, I was supposed to be back at work straight after school and I’ve come all these years surviving.
“I’m just enjoying the run, I’m loving it at Leigh now everything is an experience for me.
“I was looking around the squad and talking about the good mix of young players and old players, and I had this moment where I thought shit man I’m one of the old players now.
“I’ll just enjoy the next two seasons at Leigh and go from there.”