Willie Nelson believes in reincarnation

He told CBS News: "I think we probably come back as ourselves, pretty much. I don't believe life ends, ever."

Asked by host Anthony Mason if fans will always have him and his songs, Willie added: "I'll be back in a minute."

The 'Blue Skies' singer admitted he's amazed his career has lasted so long.

Asked how he has maintained such a long career, he said: "I don't [know] either. I have the energy to do it and the desire...

"I haven't quit. I'm 90, maybe I should."

But Willie admitted he often thinks about retiring.

He said: "I quit every night. After every tour, I say this is it. And then I get the urge again to go back,"

The 'On the Road Again' hitmaker still practices martial arts every day, which gives him "confidence".

He added: "I don't have to worry about anything."

The veteran country star holds a fifth-degree black belt and started out "in kung fu, went over to jiu jitsu, judo and taekwondo."

He added: "We had a saying in Abbot, Texas, where I come from. You only do three things down here: fight, f*** and throw rocks. So, that's what I grew up [with].

"So, we fought everything and everybody, each other, we fought bumblebees on the weekend."

Willie has long been an advocate for marijuana use but revealed earlier this year he has quit drinking and smoking to extend his life.

He noted to People magazine of his abstinence: "That's added a few days to my life, I'm sure."

Willie admitted his hearing is "not the best" any more but he still feels young at heart.

He said: "I still have a good time."