Yep, I know the feeling.
Before I read
The Art of Travel I had no idea about how to travel. I went to Europe with a class and then we stayed over and toured independently afterwards. Never having been on a multi-city european vacation, I was only concerned with my bag around the Airport, trainstation, etc. I NEVER thought about lugging my 50lb bag up and down the Paris subway across three trains changing platforms each time! It wasn't a problem before because I was riding in a coach with the class. Afterwards, I understood the hell of trying to get my extra large bags through the turnstyles. I got looks from the locals like "Why the hell do you need such a large bag!"
Hehe, they say that experience is a hard teacher because she gives the test before the lesson!
Long story short, I ended up sending some of my clothes home in London via Parcel Force. I couldn't find a UPS, but I was desperate.