How do you take breaks throughout the day?

I’ve been working from home a lot more often recently, and without the commute and normal hum of office activity and side-conversations, I’ve been having a hard time stepping away from the computer.
I’m confident that I’ll be substantially more productive if I can break up my work in the right way, but I’ve been finding it difficult to build the right habits and reminders.
So, how do you break up your work throughout the day? How often do you take breaks? And what do you do during them?