The Pomodoro Technique is a time management method (the website explaining it all is here) and it's hands-down the most valuable writing tool I've ever learned. Taking it on board has completely transformed my working life. It's enabled me to cut my working hours by half, to get all of my other tasks done and - most importantly - it's brought a sense of real calm to my writing practice. Which is no small matter.
Sometimes, when I tell people that I do it, they say, 'Oh, yeah, that thing where you work for twenty-five minutes and then take a five minute break? Yeah, I tried that.' The PT is so very much more than just a timer. If you want to give it a go, read everything you can find on the website, or, better still, buy the book. I think it's a bloody miracle.