Butterflies and Choice

I’ll try to speak good English, I’m from Holland, 24 years old and read your books with much joy. But this dilemma keeps me busy:

A caterpillar makes a cocoon and naturally transforms into a butterfly. If he would fight against the fact of being a caterpillar and make his own wings out of leafs or be depressed or in any other way distrust any force of nature, he wouldn’t ever make a cocoon. But on the other hand when he would deny his limitations as being a caterpillar and would pretend to be just as free as all butterflies he would never desire progression and so never make a cocoon either.

So now my question is; as being a human .. where is the border of acceptance and taking action?