“What we do see depends mainly on what we look for. ... In the same field the farmer will notice the crop, the geologists the fossils, botanists the flowers, artists the colouring, sportmen the cover for the game. Though we may all look at the same things, it does not all follow that we should see them.”
And so different people will notice different things in the same situation. One person will notice opportunity where another sees despair.
If we focus on our goals and vision, we will start noticing them coming alive with each step we take. If we focus on the positive in every situation, we will notice our mood lightening up. Our happiness depends on nothing other than our perception of the situation we are in.