Endurance and strength are the foundations of a good fitness plan and good health in general. One should not be ignored in pursuit of the other for long periods of time. These are some endurance workout options at a variety of intensities that you can work into your schedule throughout the week. It is advisable to not do more than two high intensity interval training sessions a week both for safety and efficacy, so choose your methods wisely.
If you are training for an endurance event, you need a specific program that will gradually increase your intensity and volume over time. A solid strength base will only improve your performance.
For general endurance, you can use these workouts either between strength training days or four hours before or after a strength workout.
Option 1 (moderate intensity): Run or Jump Rope 1 minute followed by 1 minute of rest for 10 rounds.
Option 2 (high intensity): Run, bike or row 6 rounds of the following intervals: 30 seconds all out effort followed by 2 minutes of moderate pace. Complete all six rounds with no rest between intervals. Include a 2 minute warmup round at the beginning of the sets. (I like this workout, it burns a lot of calories and increases overall power production.)
Option 3 (low intensity): Run 5K, Bike 10 miles swim 1 mile, or row 5K. Keep intensity low, total workout time should be 30-45 minutes.
Option 4 (high intensity): Complete one 50 meter sprint on the minute for 8-15 minutes.
Option 5 (low intensity): Walk 45 minutes at an incline on treadmill or over hilly terrain.
Option 6 (high intensity): Tabata intervals. Choose 1-4 exercises, these can be bodyweight exercises or cardio exercises. Performing 1 exercise at a time, perform 8 consecutive intervals of 20 seconds on, 10 seconds off, for 8 rounds. Rest 1 minute if necessary and move on to the next exercise. For a useful tool, download the Tabata Timer.