It's one thing to say you'll pack light, and another to actually manage it once traveling. Just in case you need a few reminders why it pays to pack lighter....
1. Ease of movement - less physical/mental stress when you're on the move.
2. Less stuff means you're better able to account for what you do have (before leaving that bus terminal/hostel/couchsurf/etc).
3. It's easier to pack up in a dark hostel room at 5am for that early bus/ferry/flight without waking up the whole room.
4. You'll garner compliments and envy from the 99% of people with more stuff than you.
5. You can take your pack as carry-on luggage for flights - negating any concern about misdirected/lost luggage during air travel.
6. Leaving home with the bare minimum means you leave room to carry food or souvenirs without breaking your back (and spirit).
If I truly wanted to go superlight, I think I could drop down to just a medium size daypack, however I'm not *that* hardcore. Happy Packing!