There is no such thing as mentally optimal. Everyone is far from perfect. Even so called normal people suffer neurosis, or are cruel to others, or are irrational, or are pathological liars. They don't get labelled with a mental illness because they don't submit themself for any diagnosis. They have such huge egos they would not accept that they are anything other than mentally healthy, even if their morals or rationality is quite low.
I start to hear excuses sometimes for why I am the way I am. And I start saying to myself that I am mentally ill, but actually I'm not. There are only two options: Either I'm physically ill, meaning I have brain damage or something that physically stops me from thinking properly, or I am not. I think most people have something in their brain that is stopping them from thinking properly, whether that is lack of development or damage from heavy metals or chemicals or trauma, so most people are on the same boat, even the smarter seeming people.
The less I excuse myself, the more things I do. My room isn't messy because I'm mentally ill. My room is messy because I'm tired and lazy. It looks daunting. I'm not mentally ill at all. The only difference is some people would see this and feel ill and tidy it right away, whereas I procastinate to do other things. But it is also now making me tired seeing all these things, I will put them away.
I think the takeaway message is that with enough time, you will see so called non-depressed "normal" people are just as "ill" or crazy as people willing to admit their life or behaviours are not perfect. The people who find themselves labelling themselves depressed or seeking help from councelling or doctors are just the people honest with their feelings. There are other venues too, to just talk about it, or blog about it. When I see a councellor, the most beneficial part is her listen, actually its not much about advice or what to do. So her rationality isn't any better than mine, she just offers support and some perspective. Actually I just like talking to her, so I don't have any therapy regularly and still manage in my life. And other people think I'm fine. So I just realised this morning so what if my room is a mess, I'm fine, I just haven't tidied it up!
We compare ourselves to others too much. Noone is superman or superwoman. They might look perfect on the outside, but there are probably things happening under the surface we can't know.