The midfielder switched to St James' Park on a Bosman transfer from bitter rivals Sunderland last month.
Alan Pardew's side will travel to New Zealand and Germany in their pre-season campaign, but Colback is looking forward to the hard work that lies ahead.
He told the club's official website: "It's been good, it's nice to be back. The lads have been great and very welcoming.
"It's good to have a lot of games to play - that's where you're going to get your fitness and your match sharpness and start getting a feel for the game again, which you maybe lose a touch from being off for so long.
"But it's good that we've got the weeks broken up with a lot of games.
"Obviously every game you play, if it's a friendly or not, you want to win and have a positive result, but we also need to show that we're gelling as a team and improving as a team.
"I think the manager and the staff will probably first and foremost look at performance and fitness, and if we're doing what they're asking of us then the results will come."
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