Steps

I knew someone once who was suffering depression. They said it was like falling down a dark well with no hope and they couldn't see because of the darkness.

As they were recovering they described the illness as seeing the light at the top of the well and over a period of time they had to climb the steps one by one to get to it.
Everyone at some point has to climb steep steps and open their own door to get to the light. Sometimes its a case of choosing the right door to open.