Fear with Starting a New Job and using the model

I have been in my same job for 12 years now for the City of XYZ and have made some wonderful friendships and accomplished a great deal. Over the last year, I was offered three Management positions within the City of XYZ. The first one I accepted, then turned down 3 days later because a few of my work friends told me of the horror stories about how bad the new job would have been (this was back in September of 2017) so I called back and turned down the offer. Then in October, I discovered The Life Coach podcasts and started reading Brooke’s book Self Coaching 101. I began to regret turning down the Management job back in September because it made me realize that it was my own thought process that invoked so much FEAR into the mix that it could have prevented me from a great career as a Manager. Now here I am about 8 months later and I was offered another Manager job, but turned it down for good reason (the pay was not what I was expecting) but then the unthinkable happened when I received a conditional job offer working for another City agency doing work that is totally different from what I am doing now. When this job first came out, it was the job I really wanted AND it is a Manager job.

I signed the conditional job offer recently on May 7th pending security clearances which they told me would take about 6-8 weeks time. During this waiting period my thoughts have started to wander into dark places and FEAR is starting to set in again. I am afraid to start with a new set of people, what if no one likes me, what if I cannot accomplish all that was brought up or mentioned during the interview. What if I become a target because the person they originally wanted who is temporarily in the job now will be removed when I come on board so she may try to target me or turn people against me. What if I fail ? I keep trying to tell myself that these are just my thoughts and as Brooke says constantly that the BRAIN always wants to seek comfort and does not like change and will tell us negative things to avoid the discomfort of change. I am trying really hard to change my thoughts but my FEAR just keeps overcoming me. I have 6-8 weeks to figure it out but I really know that deep inside, I HAVE TO TAKE THIS JOB. Why? Because I can start all over again with a clean slate and re-brand myself AND it will be so challenging for me which is what I need due to being too “comfortable” in my current job right now.

What is even better is that this job could be a testing ground for how I either sink and give in to negative thoughts or swim by changing my thought process and making it a positive and successful career choice. I want to go all the way up to the top. I know I have it in me, it’s just this crazy FEAR that creeps in and messes with my head and makes me start to feel anxious, afraid and emotionally clingy to what I already know and want to instantly revert back to. How I hate these thoughts so very much.
Please help, any advice on how to combat this fear with the model would be greatly appreciated.