Dreaming for what we can never have-Why do we hanker after what we can’t have?

“We all want things we can’t have. Being a decent human being is accepting that.”
John Fowles, The Collector

According to anthropologist Helen Fisher, levels of dopamine — the pleasure chemical in the brain — continue to rise the longer you must wait to fulfill your desire (Elite Daily).

Is it a way of our subconscious telling us we don’t want what we think we want? For instance, you’re single yet desire someone out of reach, is that a way of our minds telling us we don’t really want or need a relationship yet? To slow down? Is it forbidden fruit, as in when your parents say “don’t touch the drinks cabinet”? So you sneak a glass when they’re out for the evening (and then feel ill and have to try hide why). Or your diet plan says “don’t eat that chocolate bar” so it’s immediately all we think about, crave, desire, the feel of smooth chocolate melting on your tongue … sorry, I got a bit lost there.

Sometimes wanting something out of reach is good, it helps you rise out of your comfort zone and chase your dreams. It gives us that impetus to strive harder, be better, reach higher. My question I guess is – when do we know what we desire is good or bad for us? Where is that line drawn between wanting for the good of our soul, mind, body, and wanting because – well because we can’t have and deep inside know it will be wrong for us in the long run? How do we tell the difference?