Hiya, I have a 15 week lab called Willow and she's doing brilliantly with every other aspect of training but she's suddenly hating her harness when I approach her with it, and she doesn't want to go out for a walk and will sit/lie down and not move. I don't want to pull her of course, I don't want to make it any worse but I can't find any information on how to go about this. I'm really looking forward to some advice and to get this issue sorted so she (and we) enjoy our walks again! Thank you!
Is she too heavy to carry? If not I would carry her then let her walk home 'till she starts to enjoy it again. A lot of pups go through this phase at this age or a bit earlier - it doesn't usually last long
What type of harness is it? Could it be uncomfortable for her? My Willow also dislikes her harness, and whilst it's been quiet, I've been just using a flat collar, but will go back to the harness for the winter, since it's busier. I've started doing some desensitisation training with it, trying to get positive associations with it, and when I last had to use it, a couple of weeks ago at a "fun day", she was quite happy to have it put on. I've never had any issues with mine not wanting to walk, though, so if the issue is her associating the harness with the walk, rather than the walk with the harness, you have a different problem to address. I assume you've tried using tasty treats?