Anyone who starts playing at 44 and has aspirations of becoming a GM will become disillusioned rather quickly.
However, anyone who starts out playing at 44 and just wants to work hard to improve may be pleasantly surprised.
It is possible to improve as an adult. I started playing chess again at the age of 37 after a layoff of 19 years (1992-2011) and three years later I have gained 300 rating points.
It's important to have goals, and to break them in to segments which are more easily attainable.
My goal is to become a master, and has been since I was 1500 when I started playing again. But I broke that down into smaller goals of getting to 1600, then 1800, which is where I am now. Now the focus is getting to 2000.
However, for those saying that age is never a barrier, you are way wrong. When I was younger it was much easier to study chess all day. Now I have a job and a wife. I still manage to study between 2-3 hours a day, and sometimes even 4-5 a day on weekends. But it's harder to learn from those study sessions than it was 25 years ago.
However, as ponz pointed out, there are resources available today which weren't always around (for example, today I can easily access a database of millions of games...when I was a kid my "database" was games from old books and magazines that I'd copy down from the library on notepads...)
My point in all this is to be realistic and you will be able to make progress. Be unrealistic and no one will get to tell you "I told you so" because you will just slink off into the night with your tail between your legs.
Also, the point made early on in this post that it's possible to become an IM in five years from starting to first play...yeah...ok...
On the plus side, he'd get into the Guinness book of records as the oldest person ever by some distance.