Whether you see the glass as half empty or half full, you are right. You may see the world as a dangerous place requiring constant vigilance, or as generally safe. Such an attitude extends beyond
mere pessimism vs. optimism. Rather, it reflects how you feel about yourself.
To worry is to expect a negative result. If you worry enough, negative experiences are commonplace. Why? Because you expect them; and that negative expectation causes you to interpret ambivalent experiences (meaning they could go either way)as negative. That means you also experience negative events more intensely.
Negativity is a self-fulfilling prophecy. You don't even have to see the cup to assume it is half empty. A song lyric from the old comedy review, Hee Haw, expressed it as "If I had no bad luck I'd have no luck at all."
A common admonition is that you can choose to be happy. If only it were that easy! In order to make such a choice you need to feel worthy of love, you have to love yourself; and that becomes the sticking point.
A negative sense of self can be transmuted to positive, but only at a subconscious level. That is why hypnotherapy is so effective at helping overcome negativity, a dis-ease that causes folks to feel uncomfortable in their own skin.
When you have suffered enough, the real choice is to ask for help, to see yourself as worthy of the change you want to become.