I know for certain my cat helped to save my life when I was drinking. Pets have an amazing capacity to give love. I have two Siamese who I love dearly. But, they also require a lot of care.
One thing I have learned over the years is that you need to think of the long-term. What might your life be in 10, 12, 15 years? Will the dog still fit with your plans? I got a wonderful dog when I was newly married, but 7 years later when I had two small children, life with a big dog was very difficult.
And, I think it's also important to know that, if your pet gets sick, you owe it to him/her to take care of the problem and it can be costly. I just got back from the vet this morning with a bill of $320.00 and we don't even know what is the problem yet.