Dom,
I think you're right that people who do not suffer from anxiety/depression do not understand how overwhelming it can feel. My husband would say to me 'don't worry' or 'cheer up' and I always felt so discouraged with myself because I couldn't.
You talked about an example of worrying about a meeting with your boss, then a few minutes of relief and then on to worry about something else. That's what anxiety does. It will always find something in your life for you to worry about and if there isn't something obvious, it will create something for you to worry about.
And, don't feel guilty about taking a pill. I have taken an antidepressant for 6 years and for me, it works. It's a chemical imbalance and can be corrected. I'd rather not take it, but I remember my life before and I will continue.
I wish you well with the Lexapro. Keep us informed about your situation.