When I returned from Vietnam in '66, I had about 9 months left to serve, and they sent me to Camp Lejeune, NC. (When I left Vietnam, they said I could put in for any duty station in the Corps, so I put in for Kodiak Island. Like most things in the Corps, there is a significant difference between being able to "put in for," and "getting orders to.")
But other than finding out that Camp Lejeune had a great NCO club, I also found out that they had a base library with books on every profession out there. Nowadays, I suppose that information is also available on the internet. It was worthwhile having that 9 months to think about what I wanted to do with the rest of my life. I think I considered about every profession they wrote about in those books.
The only mistake I made is that I was tired of being out in the rain all night, and I probably put too much emphasis on getting a job where that wouldn't happen again. I should have thought that there was a reason I joined the Marines, and a big part of that reason was that I loved being outdoors. I don't regret my choice of a profession; it has been good for me. But I have had to get all my outdoor activities separate from the job. It doesn't sound like you're going to make that mistake, but there may be other annoyances that you might place too much emphasis on. Look at the big picture.
Every job I've had since then, it has been an advantage for me to have been a former Marine, either because people show me more respect because of it, or because the mental discipline I learned in the Marines has helped me get the job done better.