I think this is a real problem. My DS1 suffered from it badly. Looking back, I can see it started around his reception year, and writing was the issue for him. Up to that point, everything he'd ever done had come easily and naturally to him - climbing, running, riding bikes/trikes, building things with lego and yoghurt pots, reading, talking - it had all just come naturally. But suddenly he was expected to do something that didn't come naturally, and he didn't like it at all.
Looking back, I can see what I would have done when he was very young: I'd've given him more opportunities to do things that were difficult, and minimised or 'talked it down' when he failed. "Can't you do it? Oh well, never mind!" As it was, I tried to be very 'enabling', and praised and encouraged and effectively 'protected' him from having to deal with any failure.
It's harder to see what to do about it when they're teens. It's hard to see how one can create little opportunities for them to 'practice' failing, safely, and without much fuss; but I think we should if we can.
A wise friend of mine observed that fear of failure tends to become a vicious circle, because if they never push on through the fear, they forget how good success feels. And they come to associate trying with only the fear and anxiety they feel beforehand. :(
That certainly seemed true for my son, and it became a real problem.
I talked to him about it. That insight did seem to help a bit. I emphasised how bad 'not trying' was making him feel, and how good it would feel if he succeeded. In the end, right at a major crunch point where the stakes were high and the negative fallout would have come quickly, and in the face of major fear and 'fight or flight' instincts, he nevertheless gathered his courage and tried. And thankfully succeeded. It was a real turning point for him.
I wish you luck with your DS, twosteps.