Diablo Rouge - I concur. When I have attended courses or been staying in a Mess, I eat like a horse, with predictable consequences. I also agree with the earlier post basically stating that your attitude to fitness before leaving the service determines fitness/BMI after leaving.
I know that when I leave, there won't be any 'slipping down to the gym for some phys' when it is a bit quiet at work. My new job is likely to come with a top gym membership, yet when I speak with city folk few, it seems, find chance to visit the gym - either too busy mixing with clients, or headhunters!
I received last week an email from a US military facility near where I am working advising, that due to 'numerous requests' the gym would be open form 0500. Keen or what? But then, our American Cousins do tend to be in bed by 9 pm.