Surge

A "surge" is a word I use to describe a running workout I do at least once a week. *note: others might call this speed work but since I'm not up to speed yet I call them surges.
I run one mile slow and then the second mile I sprint two mailbox lengths, jog two mailbox lengths. Bursts of increased intensity when running improve cardiac strength as well as overall muscular strength and allow for your body to prepare for longer endurance runs much more quickly. Start by "surging" for 10 seconds, jogging for 50 seconds, and repeat 5 times. These 5 minutes will make a huge difference in your pace for your next running workout. You'll be able to tell a positive difference for sure.

Happy running.