He said: "It's extremely different to this time last season. There's probably more sessions in a day here than I had in a week at Bedford, which is good - I'm physically testing myself.
"But that's what I've been working towards. I've wanted to be full-time for a long time so it's been good. It's a massive step up from the Championship but I'm really enjoying all the hard work."
Stephenson had less than two weeks off after helping Bedford to the Championship final, where they were defeated by Newcastle Falcons over two legs.
But he says he was keen to move to Worcester as soon as possible and settle in to the area ahead of the new campaign.
He continued: "I came straight off the back of last season and I'm feeling quite sharp. I'm glad I came in early because I got the fitness testing done and I've shown where I am.
Getting to know everyone has been excellent and I've now sorted out my living arrangements so it's good to get all that out of the way.
"It would have been amazing to finish on a high with Bedford last season but Newcastle were the stand-out team from the outset so it was always going to be difficult.
"I think Newcastle will be competitive in the Premiership. They'll feel they've done their time in the Championship and they won't want to go back down."
Stephenson is hoping to get his first taste of Aviva Premiership rugby when the season starts in September but insists his main focus is on impressing during pre-season.
He added: "I'm trying to keep a lid on it at the moment and not get too excited. The start of the season is a while away and there are a lot of gains to be made and foundations to be built before that.
"Hopefully we'll be a really fit, fast and strong side come the start of the season. Everyone is trying to show what they can do and there's a good spirit in the camp."