Antonio Conte's side stormed to the Premier League title with a record-breaking 30 wins last May in a campaign in which the west Londoners did not have to participate in the Champions League competition.
Hazard said: "I think the Premier League is difficult.
"It's hard to win every year. Last year we didn't have the Champions League. This year we have less time to be ready for the games. Every week there are three games.
"We changed a couple of things [last summer], we lost players, we brought some new ones and every year is different.
"That's why we love football - if there is only one team that wins it would be boring. That's why football is special. You never know what's going to happen, especially in England."