If you work in a company, chances are you travel to the office or factory or other place of work five or so times a week. You wake up in the morning, have breakfast, maybe take a shower, get dressed, get out of the house, and hop into your car / bus / train / metro / helicopter / limousine or whatever you chosen commuting vehicle is. Or you walk. But some way or another, you move from one place - your home - to another - the workplace - in order to work.
If you are a small company entrepreneur that has no external office, or if you work remotely from home, you have no commute. You wake up in the morning, and since you don't have to look presentable for colleagues, you don't have to shower or even get dressed. You can have your breakfast at your desk if you want to. You're at your home all day, you can go to the fridge to get a snack anytime you want, and the possibility to take a break and watch a little TV is always present.
This is all very convenient - you save a lot of time by cutting the commute and the getting-ready-for-work times. But how will your subconscious know it's time to work? How can you tell it that now is the time to concentrate, and not the time to wonder whether you should make the bed or dust some shelves?
Here's the downside of not having to commute: there's no transition routine that tells your brain it's work time.
So what do you do? You either get an external office - if you can afford it - or you create a routine at home that signals your brain that the workday is starting. For example, you do the getting ready routine - shower, clothes, breakfast - even though you're not leaving the house. Or you use a special work mug for your morning coffee, the sight of which tells your mind that "oh, we're drinking from the work mug, so it has to be work time". The routine could be anything - you're free to choose your preference.
You may have to remind yourself to do this every morning for a while, but once you've established the habit, it's a powerful tool for conditioning your brain - doing the routine clicks a switch in your brain that turns the home into the workplace, and if you neglect the routine, your brain won't agree to work, which ensures you won't see your home as a place of work or anxiety during your days off.