<human>: I have an otherwise lovely one-year old female Newfie. However, the last few days she has started flopping down in the grass after a walk or near the end of a walk. There's nothing medically wrong with her, and she's not tired or afraid. She just plain doesn't want to come back in. I take her on long walks at least twice a day (2-3 miles), and take her out just to take care of business another 2-3 times. Regardless of whether we go out to use the bathroom or go for a long walk, when it's near the time to come back in, she lies down. She's 90-100 pounds, so I can't pick her up. I've tried many things to get her in. Once or twice she came in for a toy or treat. Another couple of times she came in if I hopped around and made funny noises.  I can usually get her standing again with no trouble, but she immediately lies down again. I'm used up in the brain department at this point. If it weren't me I'd be laughing. It's really pretty funny (if you look at it in a funny dog sort of way), but I have no clue what to do. I've owned and trained several other large dogs, and I've never had this problem. I know why she's doing it - she wants to stay outside - but I don't know how to fix it. Any advice would be extremely welcome, and I'll gladly answer any questions.

Can you summarize the given text in a few sentences?
<bot>: My dog lies down after walks and I'm not strong enough to carry her cute, but stubborn, butt back in the house.