"Should we go for a run?"

I suggest. Millie is really into physical fitness, and has a great body due to this, and I really want to see her tits bouncing when she runs.

"Matt, my tits are too big for me to run." Millie says, while she cups her tits and looks down at them, then she says:

"But you go ahead, I'll be here."

"Okay." I reply, thinking that I don't want to seem clingy and not go running if Millie does not join me, so I go inside and change, say bye to Millie, then I go for a run along a really beautiful trail. It is a nice day and the sun is out, but a little after half an hour I turn around and run back to the cabin.

I go around back, and there I see Millie sunbathing topless, and I feel my cock grow hard at the sight of her big tits glistening in the sun.

Millie hears me, so she opens her eyes, turns on her side, and gives me a big smile, asking how my run was, but she makes no effort to conceal her big tits, and I am more than sure she can see my hard-on in my pants. We make small talk for a while, then I go take a shower, and when I come back she is still sunbathing topless.

She looks over at me as I come out from the patio door with a smile, and I feel my cock getting hard at the sight of her big tits, so I smile back at her as I walk up to her, and then I need to say something.