Kenshi

Strength is trained by having a full load of items, up to 25%, and carrying bodies, up to a separate 25%. So if you want to train it easily you should fill your bag up and then pick up a friend, then run around.

Toughness is achieved by getting the shit beaten out of you. Humanoids will not kill you if they can avoid it, so picking fights with them is a good way to train that. You're supposed to lose, and if you aren't bleeding to death it is wise to get back up when playing dead which gives you a massive bonus to toughness each time you do it. Hungry Bandits are the best for this because they don't do much damage and will only steal your food when they knock you out. Try not to fight slavers, because they will enslave you and steal your stuff if they beat you, which is far from a game over but it is a pain.

Do NOT pick fights with animals for XP because some of them will eat you once you go down. Stay out of the swamps especially, since they have strong, aggressive, and meat eating red spiders in them.

Health is a bit arcane. Your body parts can go as far negative as their max, so if you have 150 health for that part then you can go -150 before the part fails and you lose it/die. Different races have different thresholds. Damaged parts will have a section that must be bandaged and will continuously tick down until they are, then they will heal over time, which can only be sped up by resting in beds. If you are in a dying state then you will tick down health until you die, you cannot recover unless tended to. If you are in a "recovery coma" then you are stable and will slowly regain function until you are healthy enough to stand up again.

Never go around fighting with your entire squad. Always hold at least one person back to stealth in after the fight to stabilize and transport injured people to beds. If everyone in your squad gets put into a dying state then you basically have to reload.

There are two different types of backpacks, regular and trader (the square ones). Regular backpacks tend to be larger and are better for things that cannot stack, like equipment. Trader backpacks can stack items and therefore are far better for transporting trade items.

Automining copper is the easiest and most boring way to get quick cash. This is done by turning "jobs" on and shift-clicking on a copper resource. Pawns will mine it until the rock's inventory fills, then take it into their inventory. If you have a building with a copper storage box in it, they will also fill the box if they have a job for it, but otherwise they will just stand there waiting for a new order, so keep an eye on them. Squin has some copper resources right next to the town that let's you run to the guards if you start getting harassed.

In my personal opinion, there is no shame in modding in some training cheats if you want to. Things like weight bench and sparring mat mods are out there that can make your life a lot easier and aren't game breaking since they only train you so far. It's a single player game, get whatever mods make the game more fun for you