I was really scared for needles in the beginning, like REALLY.. I'm still a little bit scared of big needles, the largest needle I have ever injected in my body is 10mm long.
I started by watching movies at youtube, then I sat like 5 minutes starring at the needle right before injecting and just said "fk it, I'm stronger & better than everyone else, if anyone else can do it, then I can!"
I have never had any problems with injecting since then.
I'm talking about regular needles for injecting steroids, insulin etc.