You have a "go bag" at home? The kind that contains some personal items as well as some of the duty gear you have "spares" for? You should, if for no other reason than the possibility you may be called to provide mutual aid sometime in the middle of the night. What if that call takes you to another state? What if it means being there for a few days?
Buy an extra battery charger (and battery) for your mobile phone and leave it in that bag. The last thing you need when you're far from home tackling a wildfire or working a search and rescue operation is to have your mobile phone go dead.
In addition to this, you should consider having stuff such as:
• Personal prescriptions (in their original containers) and over-the-counter medication for pain, allergies, antacid, daily vitamins, etc. that you ordinarily might take
• Prescription eyeglasses (and sunglasses) and/or contact lenses and cleaning supplies
• A change of clothing (including several sets of socks and "undies"), reflective vest, work gloves, hat, etc.
• Toiletries such as a toothbrush, toothpaste, soap, deodorant, shaving kit, brush/comb, sunscreen, lip balm, insect repellant, etc.
• Food (energy bars, trail mix, powdered protein shakes, etc.) and bottled water (or better still, water purification tablets and a good canteen)