If you're going to be sitting in the one position for a number of hours, make sure you are comfortable. If you don't have an official "office chair" experiment with the range of chairs and cushions that are available to you!
Our brian likes as much routine as we can give it, it saves it expending energy on non-value adding activities and allows it to target that energy to solve real problems and look for impactful solutions! Get in the habit of having a structured work-day with similar start and finish times each day. Remember to "disconnect" at the end of the day. Define an activity that marks the end of the working day!
It can be easy to work through your normal office breaks when you're working at home. Those breaks are vital for "sharpening the saw", "recharging the batteries" (and other such analogies). It's a bit like pressing the reset button on the computer. You come back to your work with fresh eyes and a clear mind!
Make it a habbit to check in with your team, colleagues, manager, other stakeholders. Keep yourself up to date with what's going on. Keep yourself front of mind for others. You don't want your valued contributions to be overlooked. Have a virtual coffee or lunch now and again! You are the master and architect of your own destiny!
Don't forget to get your exercise in, in whatever form that takes for you, and a bit of freshair. Getting the shoulders back, opening up the posture, opening up the lungs, inhaling oxygen deep into the lungs and tummy, having a positive voice in your head congratulating you for the work you've done so far, for sticking to your routine, for staying connected etc. all act to release Dopamine, Seretonin, Endorphins ...the happy chemicals!
Remove distractions, and enjoy the tranquil bliss of being in flow, where you are lost in and utterly focused on whatever you're choosing to concentrate on. Deactivate the email notification pop-up, put the instant message to "do not disturb", ask yourself "Am I in charge of my diary or is the diary in charge of me!"