Good afternoon everyone! I'm new to multi-day or long distance hiking. Most of my excursions are day hikes within a 50 mile radius of my home outside of San Antonio. I retire from the military in a few years and have been dreaming of doing a long distance or thru hike. Does anyone know if there are clubs/organizations one can join that offers instructional multi day hikes for beginners like me?
REI offers backpacking trips for any level of experience. I've heard of meetup groups, but you can get a wide variety of experiences. If you are looking for actual instruction, you are probably better off paying for it from a reputable organization.
People here can advise you on micro-steps, so that when you are actually in the wilderness you have the experience and confidence to have a good trip. There are many test backpacking trips you can take: sleeping in your backyard; taking your backpacking gear to a campground; day hiking with you backpacking gear then sleeping in a campground; an overnight backpacking trip within a mile of your car; and out-and-back overnight backpacking trip.... Take as many small steps as you think you need.
If you are concerned about gear, we love to talk shop! If you are retired, you are probably looking for lightweight backpacking. That is not the kind of advice you will get from REI.
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.
See if there's a backpacking Meetup group in San Antonio or nearby. Such groups can be great for beginners - you're backpacking with folks who have been doing it for awhile, and you're with others instead of going out alone at first, which can be comforting.