As you grow, errr, more mature, your hair changes colour ¿ and your image changes, too, though perhaps not in your own mind.
A stone-cold killer, or just an old man who forgot to shave?
Being a writer means working at home, mostly. And it also means working alone for a lot of the time.
The benefits of this kind of solitary effort are chiefly appreciated by the laziest among us - a category that includes me - because if your only co-worker is yourself, you can really let yourself go in the neatness and appearance departments.
Who is going to complain that you're wearing the same jeans, or the same grimy T-shirt? There's no office mate to cough politely and mention that cigar smoking in an enclosed space is a violation of Occupational Health and Safety laws.
When you work alone, you're not only your own boss, you're your own colleague, too. So for the past two weeks, while I've been working frantically to finish up a script, I'll be honest: I let myself go.
I wore the same trousers for days and days. I paced the house with a cigar - both lit and unlit - in my mouth. But mostly what I did was, I didn't shave. My beard came in, full and thick.
And grey. Seriously, disquietingly, grey.
You see, when I started in the entertainment business, years ago, I was a very young man. I'm not trying to boast, but occasionally my name was attached to the German word "wunderkind", and while I don't claim to a great amount of "wunder", I really was pretty much a "kind" when I started. I got my first big writing job on a hit television series when I was 24 years old. So the image of myself that I hold onto - despite ample evidence to the contrary staring back at me from the bathroom mirror - is that I'm still, you know, young.
"I didn't expect my beard to come in so grey," I said to a friend of mine at lunch a few days ago, after the script was completed and I had cleaned myself up a bit.
"Really?" she asked. "Why didn't you?"
"I don't think of myself as that old," I said.
"You don't? Wow. Then how do you see yourself?" she asked.
"I guess I still see myself as that young guy in his 20s," I said, which was when she started laughing uncontrollably.
Then she saw my face and stopped laughing.
"Oh my gosh. You're serious, aren't you?"
I'm ashamed to admit that I was. But I really shouldn't have been. I mean, I have grey hair already - but it's at the temples where, I'm told, it makes me look sharp and dignified.
And then I remembered something that happened to me last spring, when I was producing a show for a large television network.
It was the pilot episode, and like all pilots, this one had its moments of panic and short tempers. In many ways, producing a television show is giving yourself a repetitive stress injury: it hurts because it's always the same thing, over and over.
But for me, one moment stands out. We had to replace an actor in a lead role. It wasn't something we wanted to do, of course - and it certainly wasn't a reflection on that actor's talents or skill. But all parts aren't for all actors, and in this case the two didn't match.
So we replaced the actor, and the next day I was standing at the food table - which is where, sadly, I often stand - and one of the actors nervously approached me with a question about a line. In a shaky and terrified voice, he asked: "Is it OK if I ask you another question? I'm not trying to be disrespectful. I totally respect you and what you do. I know you're a stone-cold killer, but I'm just wondering if I could flip these two lines here when I enter with umbrella?"
"Sure," I said. And then thought to myself: stone-cold killer? No one's ever called me that. I'm actually rather polite and unassuming. But for some reason, to this young actor, I was a stone-cold killer. I had just fired an actor from the cast, of course, and that probably had a lot to do with it. But I had done that before and no one had called me a stone-cold killer.
But then it occurred to me: the last time I replaced an actor on a pilot, I guess my hair wasn't so grey. I just looked like some young guy without any experience. Now, with some grey at the temples, I've got gravity. I'm a killer.
If that's the kind of fear and respect - if there's a difference between the two, and I don't think there is - that comes with a little bit of grey at the temples, imagine how much would come from my full and lustrous grey beard.
A lot, probably. But I'm not eager to find out for sure.
Rob Long is a writer and producer based in Hollywood