For two months, I traveled through five countries and lived out of one backpack. Into that pack I stuffed enough clothes for a week as long as I didn't dump ketchup on myself too often, enough electronics to keep myself entertained and connected, a collection of medical paraphernalia, a small day pack into which I could (barely) cram my DSLR and a pair of rain pants, a couple of books which I could have done without if my iTouch's battery life was better and, for good measure, I draped a windbreaker and later a souvenir sweater through the arm straps.
It wasn't always easy - the pack felt like it weighed a ton when hiking through airports. And the pack was chosen for durability and shape (regulation airline carry on size) rather than a comfortable hang on the back. Part of the chest strap got lost, which didn't help. On a crowded train in Denmark around midnight, I seriously considered just leaving the thing on the luggage rack and not looking back.
The point is, it can be done. We drag a lot of stuff around in our lives and, don't get me wrong, I love my stuff. I'm not going to fit a 36 string folk harp into this pack. "Stuff" is certainly a "first world problem", though most of the other people I encountered seemed to be carrying several times the stuff even though they were going to be traveling for a fraction of the time.
I feel lighter and I'm happy about that.