Yes, it is doable.

And I have to laugh that you are only in your forties and are feeling "old". I know...I know...I've been there. And I have three children in their forties who are feeling "old".

I'm still working on improving. My goal is 1800...I'm getting there. I probably could hit 2000...but I don't know that I want to put in the additional work. There are, after all, other priorities that I have.

Compared to my Grandmother, I'm young. But when it comes to neurology, I'm "old" in the sense that what my neurons are doing now is not what they were doing when I was young. And no amount of telling myself I'm only as young as I feel will change that :)

No, I realize all that. That's why my golf is going downhill, as well (mostly just distance at the T-box...I chip, pitch and putt better than ever!).

BUT...I'm still within my potential at chess.

And, so are you. You even said so. 

http://www.wired.com/techbiz/media/news/2002/02/50724   Good article on it. Get exercise too.

General health has a lot more to do with learning ability than age.  Most older people who have trouble learning are usually in poor health. 

Holy cow, folks! We just heard from a superior being! He/she (it?) must be right!

Here's the thing...

I played chess as a teenager. I read books. There were no computers back then. I studied, practiced...and I would usually win (this was casual, not tournament, so I'm not bragging).

Today, after a 40 year vacation (mostly) from chess, I am a better play than the young fellow I was.

This is because for the last two years, I have been studying/practicing about two hours per day (and I know that that isn't so much by those who are far better at chess than I am).

I didn't have the time to do this back then. Also, I am older and wiser in ways that give me some advantages.

If some of you guys in your 30ies or 40ies think you are getting dim witted...maybe you are right, in your case.

Hell, some people are so dim witted that they should never have taken up chess in the first place. (lol) 

Now that I've just insulted more than half the people here...I gotta run.

The woods are full of em around here (just ask sapientdust).

I find it a bit hard to believe that Reshevsky's rating ever got that low...

You're never too old, until you die.

And then you're just old enough.

Info on Reshevsky from Chess Life ( Nov.2011 ). In 1990, at age 79, he played in the US Open held in Jacksonville. He went 7 out of 9 there, including a Draw against IM John Donaldson. By this time he may well have forgotten more about Chess than most players could ever hope to learn  lol.   

not maybe, definitely!!  he was simply one of the best.

Too old to improve @ chess? Or too old to learn anything?

I just learned the basics to make and design web pages. I'm learning new Css, html5 programing and javascript.

I'm learning cosmology, physics and writing. I'm only 74 years old and my brain is probably half empty or half full.

 I don't think you ever get to old to learn chess. It's mostly repeatability of what works and what doesn't work.

You just have to retain it. But if you can't remember it, write it down.

2300? No, you're way off. The last rating for Sammy, 1991, is 2415 FIDE according to my megabase.

Good to know.

See my article on older chess players.

http://www.chess.com/article/view/older-chess-players

 it was USCF rating he was fairly inactive at the time and didnt play many FIDE events but I clearly remember 2300ish ( wonder if i can dig up old uscf rating lists sometime at the club) Which is why I brought up the question to the master.  its been a few decades so the exact timing I am not sure of but the rating is irrelevent anyway...

Reshevsky's lowest USCF rating was 2426 (he got it back up to nearly 2500 btw just before he died).

And at the age of 70 Sammy almost won the US Championship.