Thr Golden, being a working breed, needs a minimum of 45 minutes of brisk exercise each day, 1 hour is even better. If walking him is difficult, try riding a bike or other conveyance such as roller blading while he's on the leash. Additionally, you need to take control of him when he's doing this to let him know the actions are unacceptable. To divert his attention, assert your pack leader position by biting his neck area.... no not with your mouth, of course, but with the tips of all the fingers of one hand. Grab a small portion of his neck quickly and just as quickly release it in a simulated "bite". This is how the alpha male would control the members of his pack. This will divert his attention from the unwanted behaviour. If not, repeat it. At that point, he should display submissiveness, such as lowered head, lowered tail and perhaps even laying down and rolling on his back. The point is, the dog must recognize the human as the authority figure. Don't verbalize anything during this manuever and don't under any circumstances, praise the dog while he's being submissive. Simply turn and walk away. A short time later, when he approaches you of his own accord, you may speak normally and pet him. Changing the animals mind set during any unwanted behaviour is paramount and this technique works... I saw my Dad use it effectively over many years to the point that, eventually all he had to do was to raise his eyebrows at the dog. I've used this and other similar techniques as well. The dogs were much happier and content in the knowledge they were in the presence of a strong pack leader... Best of luck!