Timo Werner "lost a bit of the fun" playing under Thomas Tuchel at Chelsea after losing his place in the side ahead of returning to RB Leipzig.
Germany international Werner sealed a permanent move back to Leipzig last week, just two years on from joining Chelsea in a £47.5million (€50m) deal.
Werner struggled to live up his price tag at Stamford Bridge as he scored just 10 Premier League goals in 56 appearances, and 23 goals in 89 games overall.
The 26-year-old found playing time hard to come by in the 2021-22 campaign, starting just 15 out of a possible 38 league matches – only the 15th most of all Chelsea players.
After bringing an end to his Stamford Bridge stay, Werner has explained he opted for a return to Leipzig as he wants to play regularly again with an eye on Qatar 2022.
"For me, having fun playing football is the most important thing," Werner, who won the Champions League with Chelsea in 2021, told the Einfach mal Luppen podcast.
"I was very successful at Chelsea, but in the end I lost a bit of the fun because I didn't play regularly any more.
"I think the coach's game system didn't suit me perfectly. So it was clear to me that I wanted to take a new step. I'm at an age where I want to play as much as I can."
As well as playing a part in last year's Champions League triumph, Werner also won the European Super Cup and Club World Cup with Chelsea.
Werner was spotted in the Stamford Bridge stands during Sunday's 2-2 draw with Tottenham and says he will forever be connected to the west London side.
"I really associate Chelsea with great successes – the greatest of my career," he said. "It'll always be a special club for me. I'll stay in contact with many players from the team."
Werner contributed to 40 goals in 89 appearances for Chelsea, which was bettered only by Mason Mount (46 goal involvements in 108 games) during his time at the club.
The ex-Stuttgart star netted just 36 minutes into his second debut for Leipzig in last week's meeting with Koln, scoring from his only attempt, yet it was only enough for a 2-2 draw.
"I would have liked a win to start," Werner said. "Still, I can't complain because the team have welcomed me back and I was involved right away.
"We have a great squad here and, if we improve further, we can achieve a lot with this team in terms of trophies."