People, as a rule, overestimate how much motivation they need to do something. After all, usually you just need enough motivation to get started. For example:

One of the biggest recommendations Tim had was to simply get started. "Once we start a task, it is rarely as bad as we think." In fact, once you get started on something, your "attributions of the task change", and what you think about yourself changes, too.

Tim offered up a great tip in his book : "When you find yourself thinking things like 'I'll feel more like doing this tomorrow,' 'I work better under pressure,' 'There's lots of time left,' I can do this in a few hours tonight', let that be a flag or signal or stimulus to indicate that you are about to needlessly delay the task, and let it also be the stimulus to just get started."