The Merseyside outfit have begun a new era under the former Wigan Athletic boss, who has replaced David Moyes at the helm following the Scotsman's 11-year stint at Goodison Park.
"It's been drastically different to what we've done before but it's been enjoyable," Sky Sports News quotes Jagielka as saying.
"It's been a lot more training with the balls and a lot more concentration required, and that sometimes isn't the easiest thing when you're tired. It's been tough but pre-season is always tough."
Everton got their pre-season campaign off to a losing start with a 2-1 defeat to Austria Vienna.