Hi There
I'm a first time mum to a dog, so I am certainly not an expert. But what I have found that seems to work for Benson my 8 wk old Golden is playing vigorously for at least 30 mins before leaving, making the puppy run and dig (if you have a sandpit set up) then make sure he has two fluffy toys that he/she can sink it's teeth into, a lamb shank a pigs ear, a tennis ball and somewhere safe to sleep and water of course and then I suppose whenever you get home repeat the running around lilke crazy thing. See I got Benson at 7 wks and had one week off work with him and taught him that I would be coming back eventually by using the same phrase mine is "see you soon" even though I might have been going to the shower or out to the shops etc. Now I am away from the house for about 8 & 1/2 hrs mon-fri and I think he sleeps alot then as well chews on his bone and pigs ear.
Hope this helps!
Susan & Benson