Transitions involve facing the unknown and that typically triggers anxiety in most of us. For some reason, a blank slate of possibilities inherent in any transition prompts creative minds to conjure up lists of "what if" scenarios, most of which instill fear in our hearts and minds.
While you may believe that your negative projection into the future is necessary in order to feel prepared for anything that might occur, this is not the case. To the contrary, thinking about what you fear might happen, as opposed to what you'd like to occur, is a waste of time, energy and attention. You may discover that this thought process is a habitual reaction to the unknown and something you do spontaneously. With more self awareness, you can develop another response.
Successfully maneuvering through a transition requires nimbleness and openness to possibilities. Fear elicits the opposite, and has you "pull in the wagons of your life" in anticipation of some threatening outcome. Consciously thinking about what you desire is an effective and productive alternative to the scenarios that typically make you want to hide under the covers.
I'm not suggesting that you just "think happy thoughts", but rather, that you become clear about your intention and desired outcome(s) for your transition. While you cannot control all aspects of any change, you can control your thinking and your response to your transition. In doing so, you will shift your attention from what you don't want to occur to more appealing prospects. With this shift, you should feel calmer and more able to move forward.