21" normal duty tube -- fits front and rear tires
4 CO2 cartridges
Small mountain bike pump
Valve Threader Cable
Tire Irons (2)
Air Pressure Gauge
Adjustable pliers (nips) to remove axle nut
17mm/27mm Riders Wrench -- fits front and rear axle nuts
Large nylon ties to strap tire to wheel
Practice getting the rear axle nut off and changing the tire at home, where you might be late for dinner but not miss it completely... :))
Replace the rubber, spoke-end protector strap with a thin piece of duct tape to cover the spoke ends in the rim.
Install a second rim lock on the rear wheel. With your original rimlock at 12 o'clock, put the second at 5 o'clock.
Don't torque the rear axle -- get it tight as possible with the wrench you use on the trail -- there's a cotter pin to hold the nut on. If it's really tight, stand on the wrench.
Don't use fender bags that bolt to the front fender. Put the pump, 21" tube, tire irons and patch kit in a front fender bag from www.dirt-bike-gear.com -- it goes sideways, with strap ties around the fork legs.
Find a wrench that fits your axle, then design a metal sleeve that extends for leverage.
Check your tire pressure before every ride. With only one rim lock, acceleration and braking can cause a rear tire with low pressure to spin clockwise or counterclockwise on the wheel far enough to pull the stem out of the tube. Repeated heavy braking can make this happen on the front wheel, too.
Use Ballard irons -- they are super-strong, unbendable steel, compact and the tips won't pinch the tube during assembly.
Stop, get off and assess the damage. Then, before you decide what to do, pull out those pictures you carry of the people you love to remind you of what's really important... :))