You can qualify for an ESA letter if you suffer from a mental or emotional issue and a licensed mental health professional recognizes it.
You don’t necessarily need to go through extensive diagnostic procedures to establish a major mental disease in order to obtain an ESA letter. Some people have hidden disabilities as well, especially when it comes to emotional issues.
All you need is recognition from a licensed healthcare professional that you have an emotional or mental issue, and your emotional support animal can help you with it. They can recognize you to be an ESA owner only through an ESA letter.