Don’t let the walking intervals fool you. If you’re doing full-on sprints, this workout is harder than any regular ole’ run. Plus, it’s a fun way to shake up the dreaded 3-mile training runs.

• one minute speed walking
• one minute “jogging”
• one minute sprinting (as fast as you can)

Repeat that 10 times for a total of 30 minutes. Don’t forget to warm-up and cool-down. If you run funny (like me) I suggest  a deserted area for this one ;)