As far as I know... here in Australia you can have any type of dog as long as it wears a harness that says its an therapy dog. Where are you located?

Those are two very different things. Emotional support dogs (or animals because they can be pet really) are not regulated by anything, do not have any special privileges, and do not require any specialized training so you can get one from a shelter or pick one up off the street. Service Dogs have to be trained how to behave in public situations as well as preforming a potentially wide variety of specific jobs from informing their partners about health conditions ( seizure incoming, blood sugar low, informing others ( trained to alert house to narcolepsy fit, trained to maintain personal bubble around partner,) or trained to interact with the environment, sometimes even trained on when to disobey orders. (Blind person trying to walk in traffic. If you are not able to train the dog for these very specific behaiviours (or miniature horse is also allowed in U.S.) you will need to pay for specialized training or find a charity willing to work with you. While access for the service dog is protected by law you may have occasions you need to have paperwork proving you need the dog, that they provide an essential service for you. That means basically having a doctor basically write a pscriptription for the dog.

I have an emotional support animal that is fundamental for my emotional health. He provides comfort for me and makes me laugh all the time, which eases my anxiety and decreases my depression.