I have never had to use my first aid kit on myself. However, the most striking example (that made it all stick together in my head all these years) was on a trip to Zion NP when I was a young teen.
We were hiking to the Emerald Pools upper pool and someone had had an accident off the trail. I didn't see the injured person but know that it was significant enough that they sent for a Ranger for evac. My Momma always made sure we had a fully stocked first aid kit in our daypacks and she stayed behind the rest of our group to render assistance to the injured person until the Rangers arrived.
I have basic first aid, CPR and Wilderness first aid certs.
I carry a mouth shield (for CPR), gloves, basic bandages and wraps, moleskin, ibuprofen and Benadryl, first aide ointment and antiseptic wipes, and some styptic powder. Tweezers and nail clippers.
