The bigger the change you’re suggesting, the more it will sap people’s self-control. And when people exhaust their self-control, what they are exhausting are the mental muscles needed to think creatively, to focus, to inhibit their impulses, and to persist in the face of frustration or failure. In other words, they’re exhausting precisely the mental muscles needed to make a big change. So when you hear people say that change is hard because people are lazy or resistant, that’s just flat wrong. In fact, the opposite is true: Change is hard because people wear themselves out…. What looks like laziness is often exhaustion.
from Switch by Chip and Dan Heath