The leaders of the Premier League were working for the first time since the coronavirus lockdown in small groups at their Melwood training ground on Wednesday.
The English top-flight hopes to resume in June, with 92 fixtures left to play, suspended as of March 13.
“I woke up earlier than usual and realized that it was my first day,” Klopp told the website of Liverpool.
“It felt like the first day of school it was 46 years ago for me, but it must have been close. I dressed again in my uniform-and for the right reason, for going to class.”
The easing of government restrictions has allowed players to train in staggered sessions in small groups, with all 20 clubs agreeing unanimously to stage one of the return-to-training protocols at the “Project Restart” meeting on Monday.
As well as practicing in groups of not more than five, each player will have sessions lasting no longer than 75 minutes. We must adhere to social distancing.

Liverpool is at the top of the table with 25 clear points, with nine games to play, and only need two more wins to claim their first Premier League title. Previously, the league had identified 12 June for matches to possibly start again, but now there is an expectation that this will need to be pushed back.
Klopp said he was “very pleased” to see his players again, “good spirits” and “good shape.” He was delighted that his players had a “true break” in lockout for nine weeks, as opposed to two or three weeks of vacation each year.
Klopp added: “Of course, you can’t rest when you’re worried about the world situation, not on a proper holiday in the same way you do.”