Start by day hiking. Do some reading on the subject; go to a public library and borrow a few books on the subject. Find a mentor; this might be done in a club, or a class or with existing friends who do it. It depends (factors) on your age, available resources, etc.
I was never a member of the Scouts (a good start, whether as a kid or an adult leader (like a friend (mom) with a son needing male role models)). My first mentor was my 10th-grade biology class teacher (I just saw him yesterday (we've known each other 46 years now)). My first-day hike was 16 miles round trip with 4,000 feet elevation gain (you need not take a hike this strenuous; I was 14). Other people and groups are possible (e.g., Sierra Club, AMC, CMC, Mazamas, Mountaineers, ad nauseum; I presided over my high school's club, the Trailblazers and university 2 terms in our mountaineering club, friends were Trail finders (a school)).
Get a sense of your limits: walking distance, elevation gain, and time (your most important outdoor resource). Take lunch (from your reading, you should get an idea of what to take). Avoid buying too much of anything. It's not about the gear. In time, it's generally a good idea to learn to push your limits (but we don't want to get ahead of ourselves yet).
Some people take courses like Outward Bound or NOLS (National Outdoor Leadership School). This is not necessary, but some people like this. The whole topic of what's called outdoor education is controversial.
Start slow: walking, buying things, learning. Pick things up by slow progression. You will not learn (much) by reading or lecturing. It's about putting 1 foot before another and experiencing.
Try car camping. Learn to sleep on flat ground. Learn about and minimize sleeping bags (learn to borrow or rent if possible), foam pads, and tents (handling environmental conditions like rain). Learn about camp stoves (do learn to prime, but you can also use other warming methods). Learn to do evening things in daylight like a tent set up. A mentor watching over you (should not necessarily be an instructor (course work)) can help critique you.
Then, finally, work up to one overnight night hike. (I only did car camping later.) My first overnighter required walking 8 miles in with 4,000 feet of gain to 11,500 feet (and I think we had to carry most of our water in). My teacher also brought his young son (maybe he was 10). You don't have to do a hike this seriously. Very windy summit (a little hard to sleep), and I was back a month later (2nd overnight hike). My 3rd overnight went to the top of Mt Whitney (14.5K ft) (twice, over a weekend, with my #2 mentor).
Repeat - Take a first aid class and CPR. Pick up other skills like a river crossing. Practice with a map, compass, and GPS separately. Realize that it's not what you learn in a class but what you retain in the way of problem-solving. Transition to winter (learn to ski, not snowshoe). Learn what to pick up in the way of skills and gear. Learn to minimize (this is mathematically called the knapsack problem (what you place on your back)). Make new reliable friends. Travel the world.
Avoid adventures. Avoid drama. The last thing you want to deal with is dead bodies. Real dead bodies (friends have). Jedi don't crave adventure, and neither should you.
Taken from https://bit.ly/3FWQN5z - This article was written originally by Eugene Miya, who has been a climber and trekker since 1970s