Try to relax a bit just before the injection by thinking of something pleasant that makes you happy, then massaging the injection site by applying pressure with your fingers, which will help to "calm" the area... it's a great trick for getting rid of pain! Be aware that while you're massaging the injection site, there may be a few involuntary muscle spasms.
No need to worry: very sensitive areas like the throat aren't usually considered suitable as injection sites... so even pain gets its marching orders.
To reduce the possibility of feeling pain... hesitating isn't allowed! The injection is administered in a single movement that requires a combination of decisiveness and speed, both when the needle is inserted and when it's taken out.
Needles with the smallest outside diameter possible that are still suitable for the injection site and the type of drug and injection, allow the dose to be administered at the right speed and without causing pain, which can happen when too much of the medication is released at once.
It's well known that injecting the drug slowly and continuously helps to avoid pain. In this case, we're talking about administering it no quicker than 1 milliliter per 10 seconds, a rule that is followed specifically because it makes the absorption of the drug easier and minimizes pain.