Be clear about your goal but be flexible about the process of achieving it.
-- Brian Tracy

Nothing in the world is more flexible and yielding than water. Yet when it attacks the firm and the strong, none can withstand it, because they have no way to change it. So the flexible overcome the adamant, the yielding overcome the forceful. Everyone knows this, but no one can do it.
-- Lao Tzu

Towering pine trees grow to that size, not by standing rigidly against the elements, but by bending as the wind demands of it. People achieve greatness in the same way, by being willing and open to change, by bending as circumstances demand of us. This is not to say you should compromise your goals or integrity, but be flexible in your approach. The tree's essential nature is to grow from a sapling to a towering pine while your essential nature is to grow into greatness and in both cases a little flexibility will be needed along the way.