I can't add much more value than CocaKoala's response already has, but in the end while I don't know what it's like for them, I don't really have to. I trust the medical science and various doctors that indicate to me I have a disease that I need to treat. I believe them when they demonstrate that my behavior/inability to focus is abnormal.

Experience with depression has taught me this is the right stance to take - while I have had friends who were sad, and were able to "get over it," when I was very sad (clinical depression though I would refuse to call it that at the time) I wasn't able to just "get over it." I fought and fought and never "got over it." I finally caved and trusted the school psych grad student that was urging me to see a professional, saw a psychiatrist, got medicated, and solved the problem. Now I understand that when it comes to illness, sometimes I just have to trust my doctor and follow their advice.