International travel with only carry-on? It makes life on the road so much easier.
The most recent time my wife and I went to Ecuador, I had 10 pounds of luggage, in one carry-on bag. Ana had 8 pounds in her carry-on bag. We spent six weeks in Ecuador, at times on glacier-covered mountains, and at other times lounging on Pacific coast beaches.
Why travel so light? Simplicity. Since we had only carry-on luggage, we were in a restaurant in Quito, while others still waited for their checked luggage. When we were on busses, our luggage was safely with us, not in the hold below being cut open, as happened to me years ago when I was in Mexico.
Other travelers struggled to their hotels carrying three heavy bags. Meanwhile we were walking along comfortably with our day packs. With less to lose, less to be stolen, less to wait for, and less to pack and unpack in hotels, we had less to worry about.
My International Travel Packing List - Six Seeks In Ecuador
* 8 pairs thin nylon socks (an ounce per pair)

* 2 silk dress shirts (3 ounces each)

* 4 poly/cotton blend t-shirts (5-6 ounces each)

* 5 pair of light underwear (2-3 ounces each)

* 1 extra pair of lightweight slacks (9 ounces)

* Waterproof/breathable rain suit (14 ounces for the set)

* Light plastic camera (3 ounces)

* Sunglasses (1 ounce)

* Small chess set (3 ounces)

* Bathroom kit (5 ounces)

* Single layer nylon shorts for hiking or swimming (2 ounces)

* Thin gloves (1 ounce)

* Thin hat (1 ounce - honestly)

* Thin wool sweater (11 ounces)

* Maps, notebook and various small things (3 or 4 pounds)
My pack weight? Ten pounds. Anas: 8 pounds. We really never felt deprived. Of course, you don't have to start counting ounces (that comes from my backpacking days). What you do have to do, is reconsider how many things you really need to bring on a trip. Leave behind things you never end up using, and remember that you can buy things as you go too.
You also don't necessarily have to buy new clothes, or buy a scale and count ounces. Simply choose lighter alternatives whenever you can. Put aside your lightest jacket, pants, shirts and socks for your next trip. The goal, after all, is simplicity, not complicated planning.
Most important is to think about what you really need to have a good time, and try to limit your packing to those things. Money is the first thing that comes to mind, and it doesn't weigh much. As for the other things? International travel is about getting away from home , so why try to carry it with you?