To quote Al Pacino, who was citing Nietzsche while playing Big Boy Caprice in the film, Dick Tracy, "A man [ we use the term loosely, of course] without a plan, is not a man." You'll be relieved to hear, though, that there are plenty out there to choose from. Here are just five to consider . . .
•Hal Higdon's Chicago Plan (about €16 for the book, free from the website)
The tone of Hal's work suggests he is the "Don" of marathon running so it came as something of a surprise that neither Gary Crossan nor our own athletics correspondent and marathon veteran, Ian O'Riordan, had ever heard of him.
Still, if you go into a bookshop which has more than one book about distance running then he's likely to be there on the shelf.
His most popular title, Marathon: The Ultimate Training and Racing Guide, is certainly comprehensive enough (although reading it all may leave little time for running) and his website - halhigdon.com - looks to have the potential to be an extremely valuable resource.
His basic plan for first-timers is 18 weeks long, involves four runs a week, one day of cross training and two of rest while the longest run is 20 miles.
•Marathon Training for Dummies (about €17.50)
Tere (it rhymes with Mary, apparently) Stouffer Drenth started running at nine and is still making a living from it a little over 30 years on. Obviously, from the title, her book is pitched at beginners and it's a very useful guide, well laid out and easy to dip into for help with items such as stretching, nutrition, speed work, etc.
At 16 weeks, her plan for beginners is shorter than Hal's but it's a little more intensive.
There is only one confirmed day off with a second granted only if it is required. Also there is some speed work recommended for during runs and additional exercises for immediately after runs.
The longest run is just 16 miles which leaves rather a lot of virgin territory to be negotiated come race day.
•Irish Runner Magazine (€4.95)
Something of an institution within the sport here, the current edition of Frank Greally's magazine contains three different training schedules with runners of various capabilities catered for by Brendan O'Shea.
The one for beginners, billed as targeting a finish of less than five hours, runs over 21 weeks which means there isn't quite enough time to start it from scratch if Dublin is the race you're considering.
The first four weeks, though, aren't too demanding with four three-mile and one four-mile runs each week so if you've been running at all up to now, you may well be able to join in.
The plan maps out a very steady progression, there are no longer runs during the week and the longest weekend run is 18 miles.
There are five days of running each week, two of which involve fartleks (a type of speed work to be dealt with in a few weeks' time).
•The Non-Runner's Marathon Trainer (about 13.00)
This is another popular choice with first-timers, with the title proving particularly appealing.
The three authors taught a marathon class at an Iowa university and achieved a very high success rate. Here they put it all in print.
There's a lot more emphasis on motivation and psychology than in most other books that target new runners and if you need help in that department this might be for you. The layout is fairly dense, though, and the illustrations pretty poor.
The training schedule has, however, gotten quite a few Irish runners to their goal. It's 16 weeks long, involves just four days' running (with no add ons) and the longest run is just 18 miles.
There's a certain amount of economy to it so there are unlikely to be any records broken but they swear by it.
•The Official Dublin Marathon website (free at adidasdublinmarathon.com)
In addition to entry forms, information on training and a variety of useful links, the Dublin race's official website contains the most relaxed training schedule we came across.
To an even greater extent than elsewhere, the emphasis here is on getting you around the course.
The programme is just 14 weeks long, offers two days' rest a week and involves a considerable number of short jogs while the longest run is between 16 and 18 miles.
There are a couple of leaps involved - in the first week you go from 20 minutes to 60 and overall it aims to have you able to complete your longest training run in just 11 weeks or so - but it still looks like an interesting schedule with more variation than most and a little more appreciation, perhaps, that those attempting it aren't intending to park the rest of their lives for the next five months.