Food, a way to purify water if you're not going to be somewhere with lots of fresh, drinkable agua, a comfortable pair of shoes, good socks, a bedroll or travel hammock, and a first aid kit, especially stuff to take care of your feet. All of this of course depending on where and when you're going, but i'd consider those the essentials.
I've been looking for first aid kits. Any advice on one for two people?
You could probably put your own together, or find one online. The kit I keep in my car has gauze, self adhesive bandage wrap, antibiotic ointment, a pair of scissors, tweezers, duct tape, super glue, bandaids in varying sizes and a few nonprescription pain meds (Aspirin, Ibuprofen, Acetaminophen). Combine that with a few big sticks and you can treat a lot of injuries all the way up to a bone break, or at least stabilize someone enough to get them more appropriate care.