Being a vet I'd have to think you've had enough survival training that backpacking will be a simple transition for you. I didn't start until I was 42 and learned just be reading a couple forums. Start with short trips to test out your gear and get things dialed in and then you can work on longer ones (up to a week) and then do one with a resupply. The most important piece of gear sits on top of your torso.