Sustainable pace is the rate of work that a team can consistently maintain without burning out team members. This concept was popularized by the Extreme Programming (XP) methodology with its 40-hour work week practice, which later evolved into the more generic "sustainable pace." The basic idea is that, although a team can have brief spurts of overtime (perhaps for a week or two at a time during critical periods during a project lifecycle), it cannot maintain that pace indefinitely. This is analogous to the concept that you cannot sprint throughout a marathon.

Strategies to help maintain a sustainable pace:

• Build activities into everyday work. This avoids the problem that the activity is scheduled into a specific period and, therefore, must be accomplished regardless of how much effort it requires. For example, instead of leaving testing to the end of a project, test all the way through the project. Instead of modeling only at the beginning of a project, model all the way through only when you need the relevant information and only to the extent that you currently need.  
• Organize the project into short iterations. Short iterations provide the opportunity for small "pebbles" (which show progress) rather than huge "milestones." Continuous feedback reduces the need to work long hours. Also, it helps focus on finding ways to consistently achieve the regular deliveries.
• Adopt a continuous integration strategy. By frequently merging code, compiling it, testing it, and running appropriate code analysis against it, you increase the quality of your work through finding and then fixing defects quickly and easily. This reduces the chance of major problems in your work, thereby reducing a primary motivator of unexpected overtime. 
• Question long hours. Productivity does not increase with hours worked. Tired people are far less productive than well-rested ones.
• Recognize sustained overtime as a failure. If a team needs to work overtime for more than two weeks in a row, that is a reflection of poor planning or inadequate resources allocation. 
• Recognize that you're still working hard at a sustainable pace. Just because you are working at a sustainable pace, it doesn't mean that the team is not working hard enough. Rather, it is typically an indication that the team is a "well-oiled machine."