Packing for trips

I hate packing for trips.  Inevitably, I end up packing too much of most of the stuff and forgetting something important.  Hey, I forgot to pack my toothbrush, but that's okay because I have 12 pairs of underwear for 3 days!  Hehehehehe.  I should make a list, but that takes forever too.  Ugh.  Why can't my essentials just pack themselves?!??