Is this how I become the grumpy old man?

Sorry for the negative title.

Lately I am realizing that I can barely recognize myself.

I am in my late 30s and can sense that the daily "grind", with the kids, work, other social responsibilities, has made me the tired and grumpy old man I feared to become. Its not so much the tiredness that gets to me, it is the fact that I am slowly fading away as a person that had a sense of what he enjoys out of life. I wake up and go to sleep, doing one task after the other, paying this bill after the other. I catch glimpses of myself in the mirror, I barely know the face. I have become that old person at the bus stop that stares in the distance, losing sight of things right in front of me.