Taking it up to 3 times per week:
Please be sure to warm-up adequately for all running.
3-5 mile run at an increased pace from previous runs. You should not be able to hold a conversation while you run.
A 25-30 minute interval run. 30 seconds jogging, 15 seconds all-out sprint, 15 seconds walk as slow as you want.
On a track or a soccer field or the beach:
sprint 100 meters/yards. walk back to the starting line. Repeat 6 times.
sprint 50 meters/yards. walk back to the starting line. Repeat 6 times.
This is meant to be an all-out 100% sprint. If you don't start getting used to this type of running now, you will be very sore come August.
*If you have a workout at crossfit that is interval based, you can substitute that for workout number two.