This is too good to be true.
-or-
I'm just waiting for the other shoe to drop.
I have been guilty of the same statements. What I have come to realize is that those statements become self-fulfilling prophecies. The more you dwell on the potential negative outcomes of any situation, the more you bring them to you.
How about an experiment? Each time you find yourself thinking a negative thought about a situation, rethink the situation and concentrate on the good and accept it wholly.
All to often we are guilty of not accepting tranquility, bliss, or peace in our life when it's right there, waiting for you to enjoy it.
Train your brain to be thankful for the peaceful times and just enjoy life!
