Quick response to this blog post, which is important but misses some information.
Don't go to a chiropractor. They are pseudoscience. Talk to a real doctor. If you're in the US, like I am, I know, it's expensive. Getting your back and neck permanently messed up by a fake doctor will be much more expensive.
Code late at night if that's what works for you. It's fine. The point isn't your working hours, it's how long you've been in one place. If you find that you're more productive in the evening, don't spend too much time at the computer in the morning. And also don't spend hours looking at a dim screen in the dark, leave a light on so you're not straining your eyes.
Standing desks are fine, but a good chair and appropriate setup are also important. I've done the standing desk thing, and I found that the best setup is to have one of those desks that goes up and down (preferably with preset heights so you don't have to fiddle with it), plus those floor pads I used to use when I worked in a coffee shop, plus a good chair. That's all really expensive, so just focus on what you can afford. If you go full-time standing, you'll quickly find that your legs and feet also hurt, not just your back.
20/20/20 rule: every 20 minutes, look at something 20 feet away for 20 seconds, to reduce eye strain. Yes, taking a smoke break every 1-2 hours (whether you smoke or not, just get away from your desk and do something else for a few minutes) is important for both your physical health and mental state, but don't forget about your eyes!
Laptops honestly are fine. Laptop keyboards are not. You don't need to spend $250 on a Topre Realforce 45g weighted blah blah blah, you could drop in at your local thrift shop and buy an early 2010s desktop keyboard that tilts and has nice-feeling switches and a numpad (make sure you clean it thoroughly).
Get a laptop stand. Not a laptop cooler, an actual stand, one of the ones that lifts the laptop up to eye height and puts it on a tilt.
Make exercise a habit (or just stretching, if you're not ready to exercise). If you try to get motivated, it won't get done. Treat it like a chore, that's fine, like watering the houseplants or taking out the trash.
Reduce the amount of caffeine you use. Programmers pound Monster drinks like water. Try actually drinking water. I've mostly switched to tea (Pu'er in the morning, green in the afternoon, white at night) to cut down on caffeine.
And most importantly, call it programming, not coding. No one likes the word "coding."