Negative thinking in new job when faced with new challenges

Lately, every time I get faced with a new challenge - or the unknown - I think I cannot do it and I think that I'm going to fail.

I believe I suffer from a lowered confidence. Years ago, I felt I could do anything at work and rise to any challenge. Then, I got knocked down due to bullying and abuse, and my confidence level changed. And now, I am a total wreck.

I have a new job, and yesterday on my first day I learned that I have to develop complex, highly detailed and highly visual client presentations in Microsoft Powerpoint.

I am no Powerpoint wizard, nor am I a wizard at client presentations in general. Sure, I've done data analysis and I've presented lengthy client reports and audits, but never at this level or to this extent.

I also learned that my new company CEO has extremely high standards - almost impossibly high. I watched a video of her giving a tutorial on these presentations and what she likes to see - and she was very nit picky about the details.

So, when faced with this reality in my new job, what do I first think? My immediate thought is: I cannot do that, I will fail and I will get myself fired because I cannot rise to this new challenge or meet the CEO's standards.

And now I am worried. I woke up with worry and fear about getting fired and for failing at my new job. They fired the last guy for not being detail oriented enough.

On the flip side, in my last job I also thought I would fail when I first started. But then, over time, I met each new challenge, I overcame the challenges, and I succeeded.

I hope the same happens in this new job, but I am scared and worried. Can I build these kinds of presentations? Can I actually do this? What if I can't?

Also, I am not used to having to meet very high standards. My last company practically us present whatever we wanted to clients since there was very little oversight of my team.

So, how do I overcome my fears and negative thinking?