Question

We didn't know that getting a puppy would change our lives so much. I thought that having a puppy would be fun, but it ends

Answer 1

Answer:

It takes a lot of responsibility to train a dog.

Explanation:

It even says in the 2nd paragraph "I thought that having a puppy would be fun, but it ends  up being a big responsibility." This shows that having a puppy takes responsibility to train.