hmm...perhaps. I do feel afraid to start, afraid that it won't be any good. But I usually end up really liking what I write.
I combat critical thoughts by writing down positive things people say about me/my writing, and by keeping a record of all the positive reviews and feedback I've received. I have it saved and when I feel bad about writing I go and read feedback from people who said they loved it. It really helps.
The first draft of anything doesn't have to be good. It's allowed to be rough. Try taking the pressure off yourself by diminishing what you're doing: "I'm just going to get a few rough ideas down; I'm just going to vomit words onto the page and see what happens; I'm just going to write this purely for myself as a warm-up exercise".
I have a HUGE problem with tackling things (World Class Procrastinator) and I usually find it's because I big it up in my mind too much. I combat this by mentally diminishing things. I also find it helps to go "I'll just take a quick, five-minute peek at this" or "Lemme just jot a few ideas down really quickly". Because five minutes feels like nothing, and you're not
really doing it you're just, you know, warming up to do it, or taking a glance at it. This "I'll just do five minutes" approach really helps me get started on things.
Nothing has to be perfect first time so don't be afraid of starting. I try and make a point of consciously feeling good and proud when I do something arduous (I look at my lovely clean living room and go "This looks great! I love how tidy this is!") It makes those positive feelings easier to recall. Try to become more aware and conscious of how GOOD it feels to have that story finished, and how much you like what you write. Reward yourself when it gets done: either with a physical reward or treat (chocolate, a massage, an afternoon off to slob out and watch your favourite movies) or just a mental pat on the back and a pep talk to yourself. This gradually makes the tasks you have to tackle rewarding to complete, because each time you get it done you give yourself a warm, positive feeling and "treat" yourself. Also, as you become more aware of the postive feelings, you can recall them when you're feeling unmotivated. So when you don't feel like writing you can easily recall how good it feels and how positive you feel when you actually do it, and use this to motivate yourself.
Other things that might help:
1. Build up 'momentum' by doing something a bit easier, then switch quickly to working on your story.
2. Give yourself a goal to spend 15/20 mins on writing, and when you finish reward yourself.
3. Visualise the task completed: visualise or imagine the complete story, and use the momentum from the visualisation to kick-start working on it for real.
4. Focus by using some meditative breathing (just concentrate on your breath and try to slow and calm it). Then calmly lay out what you're going to do. When you feel calm and settled, tackle the task.
5. Incentivize yourself by offering a reward: "If I write two-thousand words I can have a chocolate bar and a warm bubble bath" or whatever.
I don't like some of these but everyone's different so they might work for you. Just try to challenge your fears and remind yourself how much you enjoy writing and how much you (and other people) like what you eventually come up with. Good luck!