Motivation is temporary; discipline lasts forever.
Motivation will get you out the door, but it fades over time. A good book or podcast might give you the momentary impulse to take your first steps along a path, but when the road gets tough only discipline will keep you moving forward.
The great thing about discipline is that it self-reinforces. Instilling the discipline to show up regularly builds consistency in your practice, and consistency builds habit. And habits are hard to shake.
It also cross-pollinates. Building discipline in one field usually enables you to apply it in other fields. You will begin to understand the benefits of sustainability, and the deep knowledge that only comes through long-term immersion in a practice.
Seek discipline, not motivation.