why do I crash when I can relax?

[Quinnderella]

I have come so far in controlling my anxiety, but like everyone I still react to stressful situations. I've noticed that during a time of stress I seem cool and calm. I can do whatever is needed to get things done without feeling too flustered, anxious or even exhausted. When the time of stress is over, however, then I get the reaction. I usedto spend my days off from work antsy, tense and edgy until I found other ways to relax/distract myself. Why does that happen? If I can stay relaxed in the moment, why can't I relax when everything is done? (I tend to do that with emotions too, so maybe i'm just weird and repressed, lol).