The short answer is dedication, focus and pushing yourself to run faster for longer than you ever have. The longer answer involves time, commitment and a little pain (but not too much if done correctly).
Stick to these strategies and that new marathon time will be well within your grasp.
1. Set your marathon goal
When setting goals for long distance running, it’s important to be realistic. If your current marathon time is 4:30hrs, don't leap to a goal of 3:30hrs. Aiming for something like 4:10hrs, or 4hrs dead on would be much more achievable, while still requiring some serious training.
2. Find a plan that works for you
So you've decided on your target time? Great, now you need a plan.
There are many marathon training plans out there. No plan is the same - they all have differing workouts and weekly mileage volumes - however, they all have one thing in common; a mix of session to help you run faster, further.
Most plans will gradually increase the number of total weekly miles each week, peaking around 3 weeks before your marathon date.
They will also include at least one long run each week, usually on a Sunday, which builds up to 20-23 miles in the final stages of training. These runs are without doubt the most important part of your training so try not to miss or shorten them.
As mentioned there are various plans out there however one that is mentioned over and over again and I have personal experience of marathon success with (sub-3 on the first attempt) is Pfitzinger & Douglas' 'Advanced Marathoning'. I know many people who have reduced their marathon time significantly using this book/plan.
The McMillan Running set of plans is also widely used
3. Manage your time well
It takes a lot of time to train for a marathon. If you're running 40 miles per week, that's around five and a half hours a week of training (at 8 minute miles, longer at a slower training pace).
Be realistic about how much time you have to 'give' to marathon training. We all have other commitments such as work and/or family. If you want to achieve your goal then sacrifices will need to be made by both you and those around you. Whether early morning, pre-work alarms, lunchtime runs, going for a run while the kids are at a club or missing out on that night out because you have to run 10 miles on a Friday evening. You CAN reach your goal but it will take willpower and effort.
Two things really helped my winter marathon training; a head-torch and a cheap treadmill bought off Gumtree.
4. Build running stamina
The science bit.
Running uses a combination of aerobic and anaerobic energy systems. Aerobic energy is where oxygen is delivered to your muscles; the air from your lungs is pumped by your heart through blood vessels and capillaries to your muscles. Your longer runs (anything over 13 miles or 90 minutes) make your body better and better at delivering oxygen to you muscles in this way. When you repeatedly run long and slow, your body adapts, your heart gets stronger, your lungs deliver more oxygen and you expand your network of capillaries.
In the early part of your training these long runs are a vital part of building the endurance needed to run for 26.2 miles - it's called 'building your aerobic base', your ability to run a long way, comfortably.
5. Build speed endurance
But you don't want to just run 26.2 miles comfortably!
You want to do it in a specific time. Which means you will need to have a target pace. For example, if you want to run your marathon in 4 hours then you're going to have to train your body so it adapts to be able to run for 26.2 miles at an average of 9:09/mi. Or 6:52 /mi for a 3 hour marathon.
We have a pace calculator here.
So if the first 6 weeks of a 15 week plan involves building your aerobic base, weeks 7-12 involve training your body to run at your target pace.
You really want to try and do this twice per week in one 'shorter' run and one longer run. SO for example on the Wednesday you would start by running 10 miles - 3 mile easy pace warm up, 4 miles at target marathon pace (say, 9:09/mi), 3 mile cool down. Then the next Wednesday, 3 mile warm up, 5 miles at target pace, 2 mile cool down. By week 12 you'd be running 12 miles on a Wednesday with a 2 mile warm up, 9 miles at target pace, 1 mile cool down.
The same on your long Sunday run, you want to be building up so that by week 12/16 you're running at least 15 miles at your target pace with warm up and cool downs at the beginning and end.
6. Marathon nutrition and rest
If you want to run a fast marathon, then don't overlook the importance of your diet and sleeping habits. Fuel and recovery are integral to your performance not only on the big day, but also throughout your training. Be sure to eat and rest well following your training runs.
The mantra 'listen to your body' is never truer than in marathon training. If you feel over tired or have a slight injury, then rest is usually the best cure.
7. Find a nice flat fast marathon
The distance of 26.2 miles is not the same everywhere! If you want to achieve a personal best time then don't choose a marathon with 3,000ft of climbing!
We've gathered together 10 of the fastest, flattest marathons in the UK here.
We also have a marathon kit checklist so you don't forget anything on the big day!