Where does inspiration come from?

I find it curious when people say that you should let inspiration happen naturally. I understand what they mean, but the sentiment behind it seems rather passive. One can always seek inspiration, simply by visiting museums or walking in the park. Hanging out with family and friends will suffice as well. The thing about any endeavor in the arts is that life is the main facilitator of creativity. Our experiences, who we meet, what we ate-all of these feed into our library of inspiration. The negative aspect of letting inspiration occur naturally is that people don’t actively seek out different experiences in life. They believe that a light bulb will occur when they sit down in front of a sketchpad.