Her actor Joaquin Phoenix is set to walk down the aisle with his yoga instructor girlfriend.

The 40-year-old Walk the Line star revealed the exciting news during a recent appearance on The Late Show With David Letterman, and he even got down on the ground to demonstrate some yoga moves.

He said, ''We go out and at first we do these breathing exercises and I go, 'I can do this. It's pretty good.' And then she says, 'We are going to get into this first position, harnessing of the hog.' The harnessing of the hog, they have all these weird animal names.

''Before I can say, 'Who's the hog?' She grabs me.''

Phoenix added, ''It's a compromising and vulnerable position.

''She gets a strap and puts it around my shoulder and she pulls me up. She's pulling and thrusting me and I go, 'Oh no stop, my back is in pain.' And she goes, 'No. Emotional back pain.'''

The three-time Academy Award nominated actor then dropped his engagement news, adding, ''This is the crazy part of the story ... we started dating. And I think she's the one. I proposed to her and she said yes!

''I don't know what that says about me. Nothing good, right?''