"You have to look as though you're intent on causing great violent damage to someone, but have the technical discipline to do it safely"
I came to London as a young actor -- I landed off the plane and pretty much on to the West End stage, which was tremendously exciting for a man of 22 or 23. I tripped into a few jobs after that ... I'm not famous, but I've had a consistent working life for 25 years.
As an Irish actor in London, apart from the very high-profile actors, there is a tendency to pigeonhole Irish actors into token parts.
I've certainly felt the brunt of that at some point, but that's the lifestyle of a workaday actor and you have to battle on. If the door is closed, find a window. If the window's closed, dig a hole and tunnel your way in.
I don't tend to go out and party [with other actors], because I've had my heyday and sown my wild oats. I've partied hard, and that's definitely a part of the acting career. There are substance abuse issues and it can often land at the door of any actor. Success in this industry can be a double-edged sword. I've known some high-profile actors to have problems in that regard.
I can only speak from my own point of view, but perhaps I went into acting, subconsciously, to seek approval. I was always vaguely interested in the discipline and the craft, but 25 to 30 years down the line, I know what it means to be an actor now. A great actor has to be dedicated to the craft of performance and to self-realisation.
I always say when we book a job as workaday actors, that's when we stop working. We spend our lives searching and furrowing, and finding and doing auditions. When I book a job, I breathe a great sigh of relief, as it means I can get off the racetrack for a bit.
Topping up your skills during the quiet times -- that's the real work of being an actor. It's about laying the groundwork for hopefully another job. It's like any business: you make yourself competitive in the market.
I didn't pass my driving test, for instance, until I was 40, and I missed a few parts simply because of that. Believe it or not, you need a full licence to drive Brad Pitt from A to B.
I recently acquired sword-fighting, unarmed combat and rapier and dagger skills. In the industry this means you're ready for something on 'Game of Thrones' or 'Dracula' -- I saw Victoria Smurfit swinging a sword on 'Dracula' recently.
I trained at the British Academy of Stage & Screen Combat. A lot of stunt people are associated with it. A lot of directors and producers go there to get people who can fight realistically and safely.
You have to look as though you're intent on causing great violent damage to someone, but have the technical discipline to do it safely. Done right, it's a bit like choreography, or even ballet.
Working in the Irish language is interesting: I understand a lot of Irish, but I can't jam or anything. I'm very grateful for the roles that TG4 have given me (JD recently played paedophile Brendan in 'Ros Na Run').
Weirdly, when I speak lines in Irish, they come out really easily. Sometimes I find it easier to be an actor in Irish than I do in English. Maybe it's to do with the beauty of the Irish language.
I've been a stage actor all my life and now that's in my DNA. Stage and film acting are both about creating a truthful character, but you create it differently. I like the collaborative nature of film and TV, but when it comes to theatre, I like the element of the unknown.
On film sets, there's what we call the art of waiting. You have to learn to wait, and wait really well. I had a walk-on part on 'Batman Begins', which basically means you're a talking extra -- an extra who might get thrown a line. I didn't get a line in the end, but I did end up meeting (director) Christopher Nolan, Christian Bale and Katie Holmes.
I didn't see myself in the film when it came out. My brother did, though.
In conversation with Tanya Sweeney
J.D. plays Willie Pearse in '1916: An Seachtar Dearmadta', which is on Wednesdays at 9.30pm on TG4