Your motive is why you want what you do. Motive is the key not only to what you seek, but how you will seek it: the mode in which you will pursue it, with what intensity, at what cost, and against what odds. With a strong enough motive, you can obtain and endure anything.
It is foolish to tread through life without carefully considering and committing to a good motive. Most people bumble through life without intentionally choosing and aiming for what they want:
A wise man’s heart is at his right hand; but a fool’s heart at his left. (Ecclesiastes 10:2)
While it may be uncommon for an individual to have explicitly calculated their motive, it is still absolutely vital to a happy and successful life. As with many things, the popularity of a choice does not indicate its merit.
With a defined motive, you can check whether what you desire is worth the cost. Almost no worthwhile goal will cost as little as you initially estimate. As you proceed toward what you seek, you will invariably encounter a greater cost than you expected. If you know the worth of what you seek, you can easily calculate whether continuing is worthwhile, or whether you should seek a lesser (or at least less expensive) outcome.