@umbra21 - That kind of stress isn't that bad for you though, as long as it doesn't happen all the time. It's the long term stress, like the kind you get in an abusive home or a hated, high pressure job, that can really do damage to your brain and cause memory loss.
We are made to occasionally go into fight or flight mode. It's just that in the modern world we get subjected to the hormones that come with it all the time in low levels because we never stop being stressed.
Mindfulness is one really good meditation technique that's been developed specifically to help people with this kind of stress. If you're worried about suffering from it, you should look the technique up, as it's easy and it can really help people to relax.