Dog owners have fewer health problems. Their hearts are stronger, because they get regular exercise walking their pets. In addition, their mental health improves. Having a dog improves their state of mind and alleviates stress, which in turn means lower blood pressure.
I was trying to change the bold part to make it less definite.
It is an opinion and not a scientifically proven fact. Not all dog owners walk their pets.
I think the mental benefit is subjective; some owners find their dog barking and defaecating a nuisance and in a way, a source of stress.