Perception is such a slippery thing.
We see what we look for. We see what we believe. We see what we expect.
The famous sociologist W. I. Thomas has said that situations defined as real become real in their consequences. If I believe there is a God, I will behave accordingly. If I believe there is no God, my life choices will take on a very different flavor. What I believe or don't believe cannot change the reality of deity or the lack there of. But it will change very dramatically how I allow it to influence my life.
If I believe that people are basically good and kind my internal reactions to life and my outward behavior will be very different than if I believe people are usually self-serving and not to be trusted.
If I believe I have worth I will create a very different reality than if I assume I do not.
There is tremendous power in how I define my reality.
Still, I do not believe in the simple "mind over matter" approach to living. As Tony Robbins teaches in his Personal Power program, if you stand next to your garden and say "There are no weeds! There are no weeds!" the weeds will take your garden. On the other hand, it make no sense to bemoan the sad state of your garden, wondering why on earth weeds had to come, wallowing in sorrow over the purslane and pigweed. Instead, the only action that makes sense is to roll up your sleeves and get in there and pull the weeds out. Then you can have a beautiful garden.
If I put on rose colored glasses when I look at the world, refusing to admit there are problems I may initially change how I feel about life, wrapping myself in a sweet cocoon of denial. But like the weeds in my tomato patch, problems left unchecked just keep getting all the more problematic. On the other hand, there is no point of borrowing trouble by going looking for danger and harm behind every corner. I can create crisis by believing it is going to be there.
The trick, for me, is to find balance and keep striving for the most realistic view that I can. I do that by gaining experience, by seeking sound feedback, and by being willing to admit to myself when I'm making mountains out of molehills or if I'm ignoring the elephant in the room.
I am best served by facing each situation that comes up face on, in it's own terms NOT with all the baggage of everything it reminds me of. I can translate coping skills from one situation to the next. But every new day, every new moment is a new opportunity. The past does not equal the future. So I will keep defining each situation as optimistically as I can muster, with a dose of willingness to accept that things aren't always going to turn out as I expect or would like.