What are some things to put in a wilderness survival kit?

I am trying to put together a wilderness survival kit to start hiking im planning on hiking a trail that will take about three days and im trying to pack as light as possible so what are some things that i NEED to have in the pack?What are some things to put in a wilderness survival kit?
mre's, knife, fire starter, map, first aid kit, cell phone, emergency blanket (the little plastic one), water and purification tablets, compass or gps, shelter (something to make a lean to), sleeping bagWhat are some things to put in a wilderness survival kit?
aluminum foil. if it rains and you need a fire, you can use this and some sticks to form a tent for your fire. Then you can have a fire in the rain. Also, you can wrap any kind of food in this to heat up and eat.