No Stress!!

I think you're mixing up stress and anxiety. Her advice is valid - it is in fact extremely important to remain as calm as possible, despite what doubts you have over your abilities.
You don't have to be stressed to be a college student. If you just work on time management and all that jazz, you won't be stressed. I know. Even if you aren't confident in what you are doing, it doesn't mean you have to let it all pile up to the point where you are stressed out.
- I'm a very stressed person, I hate when things aren't perfect and I get frustrated. But I have learnt to control that by just taking it step by step, making sure to get help if I really don't think I'm capable of what they are asking me. You need to take a step back from the situation, realize it really isn't that bad, honestly, there are so many worse things in life.
I really felt the need to respond to this post because I am someone who gets stressed out easily and I just think you sort of had a really strong reaction to that - all that Mrs Walker was saying was to not constantly spend your time worrying about or trying to do academic work. Of course we're all going to stressed out - but the key is to do everything you can to stop yourself from getting to that extreme point where absolutely nothing can help you anymore.
I hope this makes sense....