Look, you are far more likely to die in an accident or from a disease. Think of how many Marines, Legionnaires, Soldiers, and more have served in Iraq and Afghanistan, hundreds of thousands to millions have served. US casualties around, slightly less than 6,000, have been killed in Iraq, the theater I served in in 2003, 2004, and 2005. Do the math 6,000 divided by 1,000,000 = it equates to .006%.
Your training, the advancements in medical treatments, and the tactics all are in your favor, that is if you are in the US Armed Forces or our outstanding Legion and UK allies.
In the end, Joe summed it up, if it is your time, it is your time. In 2004 in Iraq our FOB had over 400 mortar and rocket strikes in 7-months, it was like lightning and if God wanted you he wanted you.
Be more concerned about drunk drivers, walking the streets of London or Chicago or any number of large cities, is far, far more dangerous.