Is God's Will Found in the Gaps of Ours?

Every so often, moving in religious circles, I hear people worrying (sometimes a great deal) that attempting to exert control over some aspect of their lives will leave no room for God's will. I ran into this most recently with people discussing NFP, where I've seen several people express variations of the concern that this post expresses:

But is using NFP to prevent pregnancy really trusting God? ... The whole idea of a married couple becoming aware of the wife’s fertile times, and using that knowledge to decide whether or not to engage in marital relations seems rather presumptuous if you really think about it. How can it be that human reasoning is greater than God’s providence and His plan to add one more soul to His Creation?

However, the concern is certainly not found only in relation to decisions relating to fertility. I've often heard similar comments made about finances, along the lines of, "I realized that I was putting all this time into trying to figure out how we were going to pay our bills, when I should have just stopped worrying and left it up to God's will." On one occasion, I offered a coworker some help on finding another job within the company because he'd been dissatisfied with his job lately. However, he replied, "If it's God's will that I move on, it'll happen. I don't want to get in His way."

It strikes me that all of these suggest a kind of thinking in which if we will something, that thing is somehow artificial, it is "our will" and thus "not God's will", whereas if we manage to attain some sort of just-letting-things-come state, we are "leaving it up to God."

Now, clearly, when we sin, we set our will above God's, choosing to pursue our own goods rather than the greatest Good. However, that formulation, in itself, underlines that even when we do God's will, we are not passive. We conform our will to God's will, acting as He wishes us to act.

If someone forms and acts on a plan, whether it relates to career, finances, fertility, or what you will, the mere fact that he has formed and acted upon a plan does not mean that he is necessarily acting in contradiction or in accord with God's will.  Nor can we simplistically assume that we if we step back and do nothing, we are allowing God's will to happen.  After all, our own actions can be the instruments of God's will.  Not acting can be as much in contradiction to God's will as acting.