On the php[architect] site they've shared the contents of one of their regularly published columns - "The Dev Lead Trenches", written by Chris Tankersley - covering burnout of developers from their day-in and day-out work.

The tech industry is a double-edged sword. On the one side, we (generally) have well-paying jobs with nice perks, but on the other, we can easily slip into not only boring, repetitive work but figurative death marches. The former is used by most companies as an offset to the latter, but that rarely works out well. This leads many developers to come face-to-face with burnout.

He starts with some suggestions of ways to detect burnout in your own life including lack of motivation, sleep, and other emotional types of signs. He then makes a list of suggestions of how you can avoid burnout in your own work:

• set working hours
• use vacation time
• take 15 minute breaks
• take up hobbies outside of development

There's several others in the list too, so I'd recommend checking out the full article for more information about each.