The longest war in American history. Beginning October 7th, 2001 Operation Enduring Freedom - Afghanistan (OEF-A), otherwise more colloquially known as "the war in Afghanistan," formally ended December 28, 2014.
Be sure that you have a support group, and ensure that your family is taken care of in your absence so that you could concentrate on your mission without added stress. Communicate consistently with your family members to maintain motivation.
Be ready for some of the worse food at the mess halls regardless of where you are at. Take time to enjoy the surroundings and try to interact with the locals, if possible. The 2 times I was there, you have to be aware that you will get some type of attack on a regular basis. Indiscriminate rocket and mortar attacks are the norm.