When you've had a hard time sleeping for a while, it makes you think you're going to keep failing.
It's hard to believe that falling asleep and getting quality sleep is an easy thing that everyone does when you've been struggling with this for years now.
After so many years of trying, you sometimes start to think that maybe you'll struggle with this forever, right? And that's not cool at all.
I started to get more confidence in my ability to sleep by preparing for sleep What I mean by preparing for sleep is just much more than brushing your teeth and getting your jammies on, it's more like a whole routine that you set up based on your lifestyle and personality that helps you get more tired and drowsy so that you will actually be able to fall asleep! If you aren't tired and drowsy when you try to fall asleep, you will probably be lying there for 30-90 minutes or more, frustrating yourself and stressing yourself out because you just can't sleep.
In this case you should get up and do something until you feel tired enough to sleep.
What I like to do to make myself feel more drowsy and tired is to grab a boring story book or something, and read it for 5-10 minutes with my mouth open, reading in a slow monotonous voice so that I'll be bored and start to yawn...
After a while you just start to get drowsy and from that mode it's much much easier to fall asleep.
It takes a couple weeks of having success with falling asleep before you start to get confident about it.