1. You're Lacing Your Shoes at Least Three Days Each Week1 of 8
In order to run a marathon, you'll need to log a high number of weekly training miles. While there's a large range for what's considered adequate, you probably shouldn't attempt a marathon if you won't be able to get in at least 20 miles per week. In order to avoid injury, it's important to spread those miles out over more runs throughout the week, rather than trying to cram them all into a couple of long runs. If you've consistently been running at least three days per week, then you can realistically add mileage to each of those runs, or add one or two more run days per week in order to get in the required training mileage.
2. You've Been Consistent for at Least Four Months2 of 8
If you have a particular marathon you'd like to run, and it's only a few months away, the only way you can really be ready for it is if you've already developed a consistent running habit and built a decent aerobic base. While the amount of time necessary to do this varies for people, four months is a good benchmark. If you've been running for 30 minutes or more at least three times a week for four months, then you're ready to take your training to the next level and prepare for your marathon.
3. You're up for Conversation3 of 8
Running a marathon is very different than running shorter distance races. It is unforgiving of runners who spend too much time outside of the aerobic zone. Many runners, especially those relatively new to the sport, run at a pace that isn't truly aerobic. The best way to tell if you're running in the aerobic zone is to talk while you're running. If you can complete short sentences of five to seven words, then you're doing it right. Once you've found that pace, you should spend most of your training time there. This will allow you to run many more miles without putting so much wear and tear on your body.
4. You Mix it Up4 of 8
While it's important to spend most of your training miles in that very easy aerobic zone, if you care about your finish time, you'll want to spend 20 percent of your time working on speed. A good marathon-training program will consist of easy runs, long runs, tempo runs and speed workouts. If you've already been incorporating a good mix of these runs into your training program, then you're ready to tackle the marathon--all you'll need to focus on is slowly increasing the mileage of each of those runs. If you've been doing all of your training runs at the same pace, now is the time to start mixing it up so that you can get the maximum training benefit from each type of run.
5. You Completed a 10K5 of 8
While this certainly isn't mandatory, completing a 10K or half marathon is a good stepping-stone on the way to a marathon. For starters, it can help you plot out your weekly training runs. Most marathon training programs will give you specific mileage and pace guidelines based on your most recent race time. While it's possible to formulate a training program based on a 5K race, pace and mileage data will likely be more accurate if you've completed a longer race. Also, by completing a longer race, you'll have a sense of how much time and effort will be required for training. Finally, it can give you a boost in confidence and a better idea of what to expect on race day.
6. You Have the Time6 of 8
If running a marathon is something you really want to do, you'll find the time to fit your training runs in, but it's important to know before you commit just how much time is involved. If your goal is simply to finish a marathon and you're OK with doing some walking, you can probably squeak by with a minimum of four or five hours of training per week, but six or seven hours is more realistic. If you have a specific time goal in mind, your training plan may likely call for running 30, 40 or even 50 miles per week. Now you're easily talking about eight to 10 hours of training every week, and that's just running time. Add in the time it takes to suit up and get out the door before your run, time spent cooling down, stretching, taking ice baths, sports massages or foam rolling, and you can tack on several more hours per week.
7. The Last Six Months Have Been Pain-Free7 of 8
The overwhelming majority of running related injuries are due to overtraining. This is a signal that your body hasn't been able to adapt to the miles you've been running, so now is not the time to throw even more at it. It can also be a sign you've been training improperly by increasing mileage or speed (or both) too rapidly. If you've been sidelined by a running injury within the past six months, and especially if you have a particular injury that keeps popping up over and over again, it's best to take time off from running, see a specialist and rehabilitate the injured area before you return to running. When you do come back, be sure to build mileage slowly and make most of your miles slow, easy ones. Once you've built your base back up and have been injury-free for a number of months, you'll be ready to take on the marathon.