A new dog in the House

My wife and I have been missing greatly our 15 1/2 year old Border collie Long hair German Shepard mix dog that we have had since he was 2 years old. When he was about 5 we also got a Corgi female puppy for our daughter who was about 7 or 8 then and now is in college at 19. So, when our 15 1/2 year old male dog (about 70 pounds) passed away we wanted to wait and grieve for him rather than getting a new dog right away. We wound up adopting this week an English yellow lab rescue dog at about 8 years old. He is very well mannered and our now older corgi made friends with him at our dog sitter's while we were in Portland recently visiting my daughter and her boyfriend. So, they were already friends and since he needed a home about 5 people were interested. But, our dog sitter had us prioritized because we were already used to a big dog in our family. He is about 90 to 100 pounds and very good natured and getting used to living with us. I'm not used to being followed around by a 100 pound dog but he is so good natured he has won the whole family over already. The only thing is I still have him on a leash in the forest and he pulls like a sled dog which is good for me because I have to walk twice as fast to keep up with him which keeps my cardio up too. Also, our corgi really gets a workout this way too as he is so full of energy and enthusiasm because he is a 4 year younger dog than our corgi is at present at 8 years old.