Grief is normal. Grief is an appropriate reaction to a lifetime event. Grief normally subsides after a time; it's still there, but not overwhelming.

Depression is not normal. When you still feel overwhelming grief years after the event, and it's affecting your everyday life and preventing you from functioning, then it's depression.

> I think the only cure to the second form of depression is to practice a healthy state of mind everyday.

I sort of agree - mindfulness and CBT techniques can be used everyday to help prevent depressive thinking.