Reacting to things we see

Have you realized that we usually react faster to things we see rather than the things we don't see?

Take for example, eating five servings of fruits and veggies a day. We all know it’s good for us. But still we don’t eat it. The main reason, as I see it, is the fact that we don’t see the ill effects, since it is happening inside the body. So we just ignore it. Just assume a condition that we get rashes all over our face if we do not eat 5 servings of veggies/fruits in a day. Wouldn’t we react to it? We sure would.