stay far, far away from the Army and marines first off.
And DO NOT think you are about the Combat Arms life without at LEAST 6 months of emulating their training regimes and speaking to former operators. Last thing you wanna be is that green kid who gets smoked during a routine patrol in Afghanistan.
The military can instill alot of things missing in your life. It gives you a purpose, friends, a sense of belonging, money and basic necessities for a higher QoL.
However do not think you can just sign up for whatever job in any branch. You still need to think long and hard about this decision and most importantly, what can GO WRONG.
Even the "cool" and "laid back" Air Force is having a historical number of suicides, especially in Security Forces (the Military Police of the AF) and Maintenance (typically the largest career group in Flying Wings). So before you sign anything, ask questions, do research, get in shape (both physically and mentally) and really get as much information as possible to make an informed decision.