Endurance training will help to increase not just your speed, but your stamina and the duration in which you can perform physical activity. That increased intensity over longer workouts is equal to higher calorie and fat burn, not to mention increased performance.
There are a few significant ways to triple your endurance, both relying on how long and how hard you can work.
Increased Time, Lower Intensity
This is the most common way that coaches train athletes, increasing the amount of time that an athlete practices, while requiring less effort. (Hence the local soccer team practicing for 2 hours, but playing for less time in the actual game.) Runners do the same thing, practicing longer runs so the length of the actual event does not seem as difficult.
If you are new to the race, as you add time or distance to your workouts, it's essential that you avoid increasing more than 15% per month. It should be avoided to add time and intensity more than every 2 weeks. This careful planning will help avoid injury and fully train you at the previous level.
Extreme bouts of all out performance followed by short rest periods will prove to be an effective way to increase endurance and make you more fit for the big event. In other words, perform the sport at your optimal performance (goal) level for 30 seconds -2 minutes, and follow those with short recovery sessions. This should leave you huffing and puffing after the hard interval so the rest is needed. As you continue training, you'll find that your rest periods will be just fine when you shorten them, while maintaining or increasing the intensity of your all out portions. Interval days should take up two days of your training week.
Hit the Hills
Challenging your body in different ways is a key component to increasing your endurance. Hills are an excellent way to do this while maintaining the sport that you love. Hill bursts will target different muscles and cause your body to fatigue to the top of the hill and recover coming down--also interval training.
When we're talking about effectiveness, sprints are where it's at. Naturally interval based exercises, sprints are super intense, and especially effective when you vary the direction. Exercises like suicides (running to a distance, back to start, returning to a farther distance, back to start, and so on) or combining front running sprints with lateral and backwards runs, challenge your body from all directions and work to increase speed.
Though weight lifting won't increase your endurance per se, participating in some resistance and weight training will prove effective at maintaining a higher heart rate for longer periods, and can be performed with an interval based, high intensity plan in place. Try lifting weights, especially to target muscles that will be utilized in your sport. For example, focus on quads and hamstrings for running and cycling, and incorporate stablilizers in the knees and ankles. Target your lats, biceps and quads for rowing. Between sets, incorporate difficult energy zappers, like a few minutes of jump rope, running stairs or plyometric jumps that raise your heart rate and target key muscles.
Whether you are training for a particular event or hoping to raise your post-workout calorie burn, increased endurance is a heart-healthy practice.