9. Running Longer
Ramping up the pace is not the only way to make your runs challenging. Build your endurance by running longer, to avoid injury increase your weekly distance by 10% per week.
10. Run the Treadmill
If you can’t run outside, treadmill is the way to go! Challenge yourself by making the elevation a little higher and the speed a little faster.
Try running using the pyramid method, the idea is to start with short repeat and increment until you hit the longest distance possible, then decrease it using the same number of increments. Sample 200m t0 400m t0 600m, 600m back to 400m, 200m, do a short recovery intervals in between.