Give yourself a break.

It's taxing to sit all day long at your desk. In a normal office environment you get up to walk to the conference room, to the break room, or leave to go to a coffee shop. When you're working remotely, give yourself the same treatment and build in breaks throughout the day. It may be as simple as a 20-minute break to go for a walk, or go on a coffee date with a friend you've been meaning to catch up with. Schedule these breaks: literally put them in your calendar. Step away, do something else, and come back refreshed.