You probably have to re-condition your entire method of thinking. First off, step out of your mind and become aware of what thoughts are causing your negative feelings of anxiety and depression. Try to be as specific as possible, and really focus on the thoughts - focus on them objectively, not subjectively (so don't take any feeling out of the thoughts). Practice this daily, and train your brain to not have these negative feelings.
There are things you haven't addressed. Things from long ago.
Life is like an arrow. Any change at the the bow will effect the trajectory dramatically.
So how was the trajectory effected? To be clear: what events/conditions/circumstances have lead to this emotional state?
The mind thinks, but the body feels. So figure out what you feel first. That tells you how the arrow flew to this point.
Then thinking will have a purpose.