Actually there is not much to the theory, I can probably fit it all into a 2nd reply.
Treat strength as a skill. Practice makes stronger.
Weight training is a deliberate stress to the body. It responds by overcompensating. You get stronger. Most people who are not juicing require a day off after a good session.
Free weights and body weight are safest and most effective. Pulley systems come second. There is no third.
Learn the big six full body compound moves and their dimensions. Deadlift is a lower body pull - weight is pulled towards you. Squat is a lower body push - you are pushing the weight up. Bench press is horizontal push, barbell row is horizontal pull. Standing press and pull-ups are the vertical push and pull. You will do these forever.
Injuries are rarely dramatic or instantaneous. Most injuries are in the joints and build gradually. They are caused by bad form. You spend your entire life improving form.
Bodybuilder moves are not strength training. Bicep Curtis and other isolation moves are of no use to us. Neither are high deep sets where you "feel the burn".
A personal trainer who is not a power lifter will never let you lift enough to get strong. A personal trainer who is a power lifter will get you injured - but not badly. I prefer the latter.
"Push through the pain" refers to the voice screaming in your head to quit. Push through that. Never push through physical pain in the muscles or joints.
Strength gains are gains in the musculo-skeletal system and the nervous system. Bones get stronger, muscles get stronger, and more connections are wired up from your brain to the muscle.
Very heavy lifts, that you can hit only one or two reps, drain your nervous system. It is restored by sleep. You will eventually get strong enough to lift enough weight to need 2 or 3 good nights sleep before lifting heavy again.
For much more on the beginner stuff, "starting strength" by Mark Rippetoe. The author is, in my opinion, a bit biased towards athletes so he offers a few opinions as facts. But these are harmless early in training.
After you've finished stronglifts 5x5 which will take a few months, buy "5/3/1" by Jim Wendler. IMHO the perfect training program, for a lifetime.
The website t-nation.com has surprisingly high quality considering it exists to sell useless dietary supplements. It's a "tips and tricks" site so you've got to read hundreds of articles before you can tell the wheat from the chaff.
Overall, everything you need to know is on the web. It's just that the signal to noise ratio is so freaking low. Learn to recognize the methods that are for "juicers" - the guys lifting better through chemistry. Stay away from those.
I think the problem is that the 15-17k pages of the Pali Canon are already hopelessly sectarian. You won't get ChatBuddha, you'll get ChatTheravada.
As an aside, this answers the oft-posed question: how could Ananda possibly have recited the entire canon after Master Gotama's death? Answer: there was a lot less of it then.
More useful is to discard the sectarian suttas, read the rest and do what they say. In my experience it is highly effective. When you realize you must be "a lamp unto yourself" then you're almost there.
The idea is don't tear down the fence until you know why it's there. But a fence across a road - it's so obviously wrong everybody wants to tear it down - not recognizing somebody with a good reason put it there. Big lesson when examining legacy code.
Then there is the Terry Pratchett version, when they move a big piece of furniture to reveal a door with a sign, "under no circumstances should this door ever be opened. " so they open the door and general madcap laughs ensue.
Group together as religions those systems of thought and their institutions that make specific truth claims about
1. Origins of the cosmos and, specifically, homo sapiens
2. Existence (or not) and nature of super-human sentient beings, their character and agency
3. What happens after death
4. Some root cause of all problems faced by individuals, tribes, nations, and humanity
5. Prescribed and proscribed behaviors that eliminate the root cause of problems
This description covers, to my knowledge, Judaism, Christianity, Islam, Buddhism, and Hinduism, all in their many varieties.
Inasmuch as I have my own answers to these questions, then by my own definition I'm religious, though I am not backed by a state-spnsored institution :)
My path is best described as Buddhist, without reincarnation or supernatural "devas" that were syncretically added even as Sidhhata Gotoma's dead body was still warm.
Then you calculate your theoretical max for each lift on this site: https://strengthlevel.com/one-rep-max-calculator
Then plug those into 5/3/1. I can't say enough good things about 5/3/1 - it gives you an elegant and consistent approach to PRs.