Everyone has their own individual reasons for serving but in the US, one strong motivator seems to be the help towards university fees once they leave.
For American military veterans, not only do they get their fees paid, they also receive a salary to study.
The sunshine state of California is home to Santa Barbara University, one of American’s top colleges.
Max Peck is the university's Administrative Lead for veterans and has looked after more than 100 students at their bespoke veteran centre.
"If you’ve served it's a no brainer to go back to school. If you’ve put in the time and effort to be in the uni why not get paid to go to school – you gave your time to the government so the least they can do is train you up afterwards."
Santa Barbara is not unique, a majority of American universities have similar programmes and facilities.
The post 9/11 GI bill states that if you have served at least three years since September 10th 2001, you are entitled to 100% of your tuition fees, a housing allowance and a stipend of up to $1,000 a year to live off.
Even those who have served as little as 90 days are eligible for a proportion of their fees to be paid.
Linking up higher education with the military has proved incredibly effective when it comes to recruitment.
US Government statistics put unemployment amongst veterans at just 4.3%, this compares to the latest MOD figures which show 11% of former personnel are without work.