We have an incredible group of people who invest deeply in our common project. Some significant portion of this group is near burnout at any given time, and we've lost important contributors, some famously, as a result of this.
The more general problem is: How can we help our contributors to manage their work so they don't get so close to burnout? How can we help people find (or regain) balance while dealing with the technical and social problems of contributing to our great project?
* Begin a concentrated initiative to grow and keep our contributors, and to keep them happy.
* Make this a goal a key project responsibility.
* Learn from other organizations and resources ways to approach this.
For background you may be interested in reading
What is burnout?
What can Individuals do to prevent burnout?
How does the Drupal community burn people out?
What can the Drupal community do about burnout?