I have the same job I've been doing it for several years and was a volunteer for some years before that also. It has never gotten any easier for me. Its not a rare thing to see me crying at work, even in front of customers. Even though it doesn't get easy, I still feel its very rewarding and very worth it. If I ever feel like quitting, I just walk into the dog kennels or cattery and look at their faces. I could never leave them, although I have switched shelters a few times