Motivation is the quiet why underneath everything your mind does: the true reason you engage with life. It runs below your awareness most of the time, and when it is clean, your involvement in things feels right and clear; when it drifts off, effort starts to feel strained and slightly false even if you cannot say why. This is part of the fourth deep transformation in your design, and knowing your true fuel lets you feel the difference in your own body between action that is correct for you and action that is subtly off.
Lived cleanly, this is a powerful engine. You will chase a thing long past the point where sensible people have given up, and every so often you find it, exactly where everyone said it could not be. Trial and error is your natural method, so the wrong turns are not failures, they are how the new gets found. When you let yourself want plainly and follow that want, life gets interesting fast, and you turn up things nobody was looking for.
The drift to watch for is a strange one: desire quietly turning into a performance of innocence. It usually begins with the idea that wanting something for yourself is greedy, or somehow unspiritual, so you stop admitting what you want and rename it surrender. You tell yourself you have let go and are simply waiting for life to deliver. What has actually happened is that you have suppressed the exact drive that is correct for you, and the result is flatness rather than peace. The trigger is almost always shame about desire itself, usually borrowed from someone else.
The correction is honesty about what you want, starting with yourself. Naming it plainly does not make you grasping; hiding it makes you dull. Let the want move you, let it take you toward the unexplored thing, and let your inner authority decide what you actually act on.