Why would activation energy exist?

Why do activation costs and the ego exist? How do they factor into the evolutionary development of our mind? Why would we even have activation costs if they make us lazy and less likely to survive? Or are these simply consequences to a self-aware mind?

UPDATE 2013-01-27: Activation energy probably exists for the same reason physical energy exists. It’s finite and wears out with use. Just as we can exercise the body, we can also exercise the mind to make it stronger and work longer. And they have limited energy because only so much energy can be stored in your muscles and mind at a time. You have to rest to recharge.

UPDATE 2015-03-16: I can also imagine that cells, energy in general, wants naturally to be at rest, and that life resists this natural tendency through its own mechanisms. In the beginning cells had minor internal functions that grew in complexity and further from that state of rest. The more complex we become, the more noticeable those forces acting against us are. Life, energy, movement is all working against the natural state of the universe. What it comes down to is managing our brain chemistry and realizing that all these systems respond to change and long-term change equates to more permanent results. Cells don’t want to work, but they will, and the more you work them the more they can shape until they run more optimally under the conditions you’re trying to reach.

UPDATE 2018-09-11: This idea that the natural state is “at rest” might be wrong. The universe is literally vibrating constantly at its smallest levels. To think that the universe is at rest seems wrong from that perspective. However, it may be that we’re “overclocking” our systems which is why activation energy exists. The system wants to be alive and move, but only to a degree. As humans, especially in modern societies, we want to constantly be active and engaged with the world which is beyond the default desire of the system. This is why we get tired and require willpower to overcome it. We’re revving the motor and expecting it to just work or have no consequences over time.