How to Sustain Motivational Costs of a Project

Motivation is a somewhat rational signal about the value of your activity. To feel motivated, the project needs to be high value with high certainty. A project can be frustrating because there are many problem solving steps that don't allow tractable progress. Emotional issues arising because of people you need to work with or the intrinsic interestingness, or lack thereof, of the subject can also affect the motivational costs of pursuing it. Even when you need to pour tons of time into one pursuit, that's often best handled by being able to drastically cut other competing work.