Los Angeles, Dec 20 (IANS): Actor George Clooney says Mathew Perry wasn't happy while being on 'Friends'.

In an interview, George shared what Mathew was like off camera as he reflected on their friendship.

"I knew Matt when he was 16 years old. We used to play paddle tennis together... And he was a great, funny, funny, funny kid,” George revealed to Deadline.

George, who made an appearance as Dr. Michael Mitchell on the hit sitcom, shared that Matthew would tell him how much he wanted to be on a sitcom when hanging out with fellow actors Richard Kind and Grant Heslov.

"I just want to get on a sitcom, man. I just want to get on a regular sitcom and I would be the happiest man on earth," Mathew said, according to George.

Despite that, the 'Ocean's Eleven' star noted that Matthew didn't feel content even when he landed the role of the funny pal on 'Friends', which also starred Jennifer Aniston, Lisa Kudrow, Courteney Cox, David Schwimmer and Matt LeBlanc.

"He got on probably one of the best ever," George said of the show, reports aceshowbiz.com.

"He wasn't happy. It didn't bring him joy or happiness or peace."

The 'ER' alum continued: "And watching that go on on the lot-we were at Warner Brothers, we were there right next to each other-it was hard to watch because we didn't know what was going through him. We just knew that he wasn't happy."

When it comes to Matthew's addiction struggles, George said: "I had no idea he was doing what, 12 Vicodin a day and all the stuff he talked about, all that heartbreaking stuff."

He added: "It also just tells you that success and money and all those things, it doesn't just automatically bring you happiness. You have to be happy with yourself and your life."

Prior to his death in October due to the acute effects of ketamine, Mathew once said that he didn't want to be remembered just as a 'Friends' star.