Billy Ray Cyrus says his daughter Miley has a ''joy for life'' now that she's stopped smoking marijuana.

The 24-year-old singer admitted in a recent interview that she had been ''completely clean'' from the drug for three weeks at the time the interview was conducted, and her country superstar father has now said he sees a ''joy in her spirit'' that wasn't there before she quit smoking.

He said: ''As a dad, I see Miley really just functioning on, like, a figure and a joy for life. I don't know how to break it down more than just the fact that I see a joy in her spirit and something coming from within that is just pure beauty, if you will.''

''I think she just found ... she's firing off all cylinders. Her thoughts, her instincts, everything is at the top of its game. Sometimes you have to clear out the junk. And then you realize what's most important. Whatever is going on, it's working for her.''

And the 'Achy Breaky Heart' hitmaker, 55, has also said he is pleased to see how ''happy'' Miley looks these days, as the happiness of his daughter ''means more'' than anything.

He told 'Entertainment Tonight': ''You know what I like about the way she looks [now?] Happy. You have even seen it. A month or two [ago] she sent me a picture and I said, 'You look so happy.' I'm here [as her dad], and she's beaming with happiness. That means more to me than anything. That's what I want Miley to look like - happy.''

The news comes after the 'Malibu' singer recently said she was clean from both drugs and alcohol because she ''wanted'' to get clean.

She said: ''I f***ing hate it when people can't adjust. I used to [resist changing]. But I haven't smoked weed in three weeks, which is the longest I've ever [gone without it]. I'm not doing drugs, I'm not drinking, I'm completely clean right now! That was just something that I wanted to do.''