My golden retriever was from a rescue centre too and I had loads of problems walking him as he'd never been exercised. I initially had a harness for him but found it quite difficult to control him as he's so strong and was pulling a lo
t. A dog behaviourist told me that it depends where the dog's strength is ie do they pull from their chest or their head. I tried the halti harness ( the type that goes across their nose and fastens behind their ears) I have found it has completely changed walking him, he now walks alongside me and if he is distracted (usually by a cat) he's really easy to control. It's worth trying one, hope this helps