One of the biggest problems with depression is, you very likely don’t know you have it. Depression screws with your mind, causing you to behave in ways you ordinarily wouldn’t. You feel that everything is pointless. Your priorities get messed up. You waste time and energy (what you have) on the wrong things.
You put things off – after all, what’s the use, anyway – and then blame yourself when you fail. You try to hide your pain. No one knows what’s wrong, including you.
Diagnosis is difficult. If depression isn’t diagnosed and treated, it can build on itself and end in suicide.
When I was on AD, I was diagnosed and treated successfully. After that, I spotted the symptoms in two other service members and convinced them to get help. One recovered. The other had close family members who told him to “man up” and that he should straighten himself out. He shot himself.
Currently, I’m on St. John’s Wort which keeps me stable and happy. It’s pretty worthless against severe depression, but useful against mild to moderate depression.