Running

I mean, just run?

Do 5ks till they're easy, then 10ks, then 20ks which are essentially "half marathons" since a marathon is ~43ks.

So basically, when you run a 20k, a 5k, and then another 20k back to back to back.

You're ready for a marathon.

If you're not a runner and you're trying to run a marathon, you're gonna give yourself shin splints and likely something even worse. Your body will adapt to those muscular skeletal stress, if it can adapt slowly you'll be better off. If it has to adapt too quickly it will fuck it up.

Like "shin spints" sound like they're not a big deal, but it's your muscles/tendons causing microfractures because your bones aren't strong enough. Try to "push thru" and you get real stress fractures, because bone grows slower than muscles and tendons.

If you really need to improve fast and no one can talk you out of it: run on soft grass as much as possible, or at least a real track. Avoid concrete and compacted running trails at all costs.

My wife just looks at preplanned training regiments that match her splits and what she's hoping for in terms of finish time and picks once that looks like it would be doable considering her schedule.

A lot of it will be gut training and figuring out what you need along the the way in terms of hydration and nutrients

I've only done one marathon, but while training for it I followed the training plan the marathon organisers put out.

https://www.sunshinecoastmarathon.com.au/wp-content/uploads/2023/04/SCM-Advanced-Marathon-Training-Plan.pdf

As a general rule, I disagree strongly with some of the advice in the current top comment. Your longest run should cap out at about 35 km, definitely not the full distance. And you should taper. Your longest training run should be a couple of weeks out, and your final week should be more focused on shorter efforts to keep your sharp, rather than on volume. You want to be well-rested for the big day.

20 km weekly is very low volume for a full marathon. Initially and during the taper that's fine, but at peak load you should probably be doing about a full marathon across the week (but not in one run!). Though perhaps this is something that depends on level. If there's anything in my comment that doesn't apply at all levels, it's this.

Run/walking is also perfectly fine if you need to, especially to prevent injury. It's not a tactic that's going to get you a sub-3hr time, but that doesn't mean it's bad. Listen to your body. Joint pain and sharp pain like shin splints is bad and you should stop or slow down. A more aching pain in your muscles might be something you can continue through.

My dad ran one full marathon and my friend is about to.

My dad did a proper training, my friend is kinda just winging it, but it's basically always the same ingredients:

• enough sleep and health, maybe a checkup beforehand
• training up to like 20km weekly (can't remember the exact figures)
• eat lots of complex calories; pasta, potatoes etc are great
• do one practice run for marathon distance to get a feel for it
• train right up until marathon, the exhaustion from previous training will physically prevent you from starting off to fast
• be consistent. The tempo doesn't really matter, but no walking, only running. Taking breaks by walking will throw you off more than you expect, trust me.
• maybe check your shoes and your running style with an expert (maybe at a shop for sports gear), it can help a lot to wear the right shoes and reduce additional issues caused by a bad running style or subpar shoes.

if you do even halt of the things and you're fit to begin with you'll probably be fine.

Every weekend do a long run that's 10% longer than last week. Once you hit 42k just run it a couple of weekends to adjust to it.