Psychology - "The Meaning of Anxiety" by Rollo May I find this very incomplete and generalizing. I could be missing the point.
But often anxiety leads me to want to sleep and wake up refreshed and elated.
The reason for this is is that anxiety can reach a threshold where the thing you are doing in spite of anxiety where the thing you are doing is not enjoyable whatsoever anymore and you're just doing the thing because of some future reward where you might conquer or evolve beyong the anxiety. This is a gamble because you might not at all.
Ofcourse there is a subtle anxiety or excitiation which you could call eustress where the thing your doing is still enjoyable even though you have a little anxiety but you can't really call it anxiety, it's just a subtle fear or excitement.
And then there is also possibly a genetic, soul-level, component where some people thrive from anxiety whilst others do not at all.