Not being able to lift 400 lbs is not a medical condition.. lifting that much is something that almost everyone would have to work towards. Depression is a medical condition because it is 1) not something a person sought out or worked towards, 2) creates difficulty in that individual's life, and 3) typically can be assisted by medical care.

Sure, you can mold your brain (something that therapy and psychiatry assists in) but people don't all start with the same brain chemistry. Trauma can also impact that chemistry.

I'm glad you have had success overcoming your panic attacks on your own. But, technically broken bones don't always need medical care. That doesn't make them not a medical condition. Same with depression/anxiety. Some may be able to improve their condition on their own, but that shouldn't invalidate people who do need professional help for a valid medical condition.