Sprints? Yeah, sprints. Stop watch. Set it to “chirp” at 20 second intervals. Start with 20 seconds at a fast jog/slow run pace. Next 20 kick it into a full on sprint. Run your ass off. Next 20, ratchet down to a slow jog. Next 20 walk. Repeat 10 times.
* before anyone makes a stupid comment about there not being any warm up here. It’s implied that you warm up prior to doing any of the listed routines.