I know it seems obvious, but you’d be surprised by how many people think they can work at home from the sofa.
I know it’s tempting, but don’t do it. Among other things, working form the sofa is horrible for your posture, will make you feel lethargic, and will make you less productive since you will likely be less organized.
Get a desk, even a small one from Ikea, and don’t forget a comfortable chair.
Get a desk lamp, folders, planners etc. Put things around your desk. Make it your own work space, like one you’d have in an office. The point is to make it feel like a place that work should and will happen in.
Creating an atmosphere like this is conducive to a healthy working mind. It’ll allow you to switch “on” when you’re at your desk, and switch “off” when you leave.