I've struggled even to break for lunch most days in my 17 year career as a dev. There are no natural intervals for me to break on and I fear losing context/momentum. I seem to always need to do "one more thing" and suddenly it's 5pm and I'm exhausted and generally unpleasant to be around.
Make it a ritual. I work in one of the Nordic countries and I see even the most productive developers dropping their jobs at 12 to have a lunch and a chat.<p>We all do it and when we come back, my output is noticeably better.<p>Another thing I've found helpful is to define a few activities I should do in my break to avoid getting sucked in by the urgency of work. These include drinking water, chatting with people and letting my mind roam without judgment for a few minutes.<p>Funnily enough, the biggest problem with taking breaks is the guilt of feeling that time is being wasted. What I've found however is that I've had a large amount of very useful discussions during breaks. Same with generating ideas about how to solve new problems.
I second making it a ritual.<p>Have a specific time when you stop for breaks. I think it was Graham Greene who would stop writing after he hit 500 words, even if he was in the middle of a sentence. Try setting times for those breaks – say, 10:00 am for a morning break, 1:00 pm for lunch, etc.<p>Just remember that it will take time to adapt to this and to form the habit of taking breaks. Do it a bit at a time and you'll get there.