Cora and Jon Hamm have been best friends for 12 years

By Mia McNiece
Updated October 30, 2015 05:16 PM

It was love at first sight when Jon Hamm first met his rescue dog, Cora, 12 years ago.

“I went to see her with the idea of fostering her,” Hamm tells PEOPLE. “But after meeting her I knew I had to keep her.”

Hamm, who can often be spotted with his Shepard mix by his side, says it’s been a “pure joy” watching Cora grow over the years.

“We think she was about one when we got her. She had all of her adult teeth but she was skinny,” says Hamm. “Now she has a little gray and probably going on 14. She’s had a good long life and she is still going.”

He adds that what Cora has brought into his life has been immeasurable.

“It has changed my life in such a positive way,” says Hamm. ” Pets can bring to us a sense of love and pride and all of those wonderful things.”

He also encourages everyone to go the shelter route when choosing a pet and recently teamed up with to help raise awareness about the importance of adopting animals in need.

“I wish more people would take advantage of pet rescue,” says Hamm. “It’s easy to do and inexpensive. Cora provides me with pure joy and love – and those are two pretty nice things to have in your life.”

For more on Jon Hamm and his furry friend Cora pick up the new issue of PEOPLE (on newsstands now).