Polar Bear, this isn't advice or anything, or even saying that you're like me, this is just what happened to me.
I've always been a quiter. I give things up when they get hard. I never put the work in, I just did the bare minimum and when it wasn't enough, I gave up.
Until recently. When lockdown started, I started using my turbo trainer with TheSufferfest videos. I've done this before, but never like this, and never with the automatic setting of resistance used so much.
Previously when it got hard, I would ease off, or stop. I would convince myself that I'd done enough, couldn't do anymore, should save some energy.
Once I got into it though, I would carry on. It was only 40 minutes, then I could stop. So I did. I started finishing all the workouts. I would just carry on. If I was tired and didn't want to continue, I'd look at the time left and see that it was just 5 more minutes, or just 2 more minutes before a rest break.
I got in the habit of finishing, rather than stopping. It was a hard habit to break, but now when I'm on the bike, or running, I know that I don't have to stop. I can carry on and I will finish it.
Your runs are nothing to fear. You can do them, you've done them before. When the fear hits you, don't listen to your heart, listen to your head. You can do it, you know you can because you've done it before. Just do another few minutes, and then another few more.