I'm not a seasoned work-from-homer, but I've done my fair share as a freelancer. Some of the biggest perks can actually be a homeworker's worst enemies when it comes to getting stuff done.
I've known people who work from home wearing pyjamas. And why shouldn't they? There's no obligation to adhere to any clothing format or style when no one can see you. But don't forget that you can see yourself, and the more you notice how comfortable you look, the greater the chance that your brain will trick you into thinking you're not at work, but about to go to bed. I'm not suggesting you fashion a uniform for work days, but create some boundaries. Clothing is a good start. This can be difficult for people who are allowed to dress casually at work. I know this well, and have found myself pulling out the same raggedy jumper whether working at home or at the office. My advice is to cultivate a level of self respect when working at home. Maybe even try wearing something slightly more formal, or even play with different styles of smart casual home / work wear. The important thing is to get your perception of what's going on into the sphere of work. Think work, dress work, enable structure.
The food item I go for continuously on work at home days is the posh person's sausage roll. There are delicious (suitably pretentious) snacks on offer in this world, although I wonder whether they'll be deemed acceptable fare in the weeks to come, when everybody's beating each other with spam slices. All I'm saying is, with your cosy little fridge closer than it's ever been for longer than you've ever known, you may start hitting the guac and crackers. To prepare yourself, try and make lunch the night before you start your working day. Like your choice of clothes, this is a structural tactic. Plan, stick to it, fight the fight people.
I once read a quarter of Stephen King's Carrie on a toilet. I came round from the experience cold and in pain. Clearly the story got to me. Wait for it, because here comes my tenuous connection, which is, don't sit too long at your computer, or in any space for that matter. There's more risk of this happening when you're working from home. This is because you don't have to walk to any meetings, get up to go and see someone, or do much else that involves moving. More technically, I might hazard using the term occupational mobility - moving as a necessary part of one's job. The way to sort this issue is to try and have two spaces you work in, as this creates variety. The other is to drink plenty of water, because, as one of my old colleagues used to say, 'you can't pee sitting at your desk'.
There's a second side to this, and it's making your work space look like it's meant for work. If you're forced to work in your bedroom, then you might need to go as far as throwing a sheet over your bed and pretending it's a large stack of files you recently ordered for your home office. If you can, try not to work in the kitchen, lounge, living room or bedroom. If that's not possible, then try reforging your informal spaces to look more formal. For some people, this might just mean tidying up. For reception / living room / lounges, there might be an opportunity to hive off a section just for work. I hasten to use the term 'productivity', partly because it doesn't necessarily apply to your day job, but also because I hate buzz words, which turn everyone into sheep. Baa!
I'm well aware of the current rules about trips out. You can only 'go outside for food, health reasons or work (where this absolutely cannot be done from home)'. Okay, so most of the space you've got to work with is inside your home. This means you have to turn your food excursions into sightseeing trips. You may have noticed our sun putting itself on display a decent amount recently. It's strange and kind of lovely. What a juxtaposition to the general feel of the world right now. There are no rules saying you can't pause to stare longer at natural light flooding the near-empty streets. There's nothing printed on GOV.UK that says don't enjoy a moment of reflection on the state of the world. Things are changing for sure, and one of those changes means you'll be able to see the end of your road. Be human and allow that primordial grasp on your surroundings to sink in. Lastly, there's no rule about taking a circuitous route to the shops - wink wink!
If you have a diary (web or paper), use it. Fill it with stuff you want to get done during each week. For work, this should be easier in the sense that you are given tasks to do. If you set aside time at work to do certain tasks, then the same should apply when you work at home. It's not always easy I know, because those posh sausage rolls are singing to your stomach, but... Try your best not to let too many interruptions in. Communicate with sensitivity and diplomacy to those nearby that you need a certain time to do work, and for a given time, you will indeed be working, and nothing else.
This applies at all times. In the world before this one, and especially when working from home, it's important to get out of you house / flat / abode. As a side note, I think the current pandemic will do something to the way we perceive interaction. It's not clear to anyone exactly what that is yet. But with this new flavour of existence, social interaction is now as remote as our work. With that in mind, make sure you organise video chats with friends. Options for video chats include Google Hangouts, FaceTime (Apple), Skype (Windows), and even Slack conference calling. Speak to people, organise something, commit to it, do it.
When you're a writer, this is particularly difficult because professional projects blend straight over to personal work. Of course they're different in many ways, but the act of being hunched over a laptop and typing is pretty much the same. You need to force yourself to do nothing very much every day. This might include reading a magazine or a book by the way, but not online. Read paper, stare at real print. Stare at a wall or out a window. Allow thoughts to simply flow in and out of your mind.
I think Bonson (Bojo/Boris etc) has said we can all exercise outside as long as you stay 2 metres from others. I'm already guilty of using the COVID-19 outbreak as an excuse to not move around very much. But I'm not going to let my own laziness be an excuse not to offer some advice on the subject. Outside you can cycle, run or walk, of course. But inside you can do pushups, like the 50 pushup challenge. The simple pushup is a body-forming all rounder. You can do an indoor HIIT workout (30 minutes of your new time-rich life). Remember to combine a bit of inside and outside living. As I can testify, vitamin D will never quite feel like a replacement for sun on your back.