EXTENSIVE
8A) 30/30: Run for 30 seconds, then jog for 30. Finish with a ten-minute cooldown run. Weeks 1 & 2: 9 reps; week 3: 12; week 4: 15; weeks 5 & 6: 18.

7G Dumbbell Pullover Photographs by Monte Isom

8B) FARTLEK: Jog for 20 minutes, evenly mixing in 12 half-to-two-minute hard runs throughout. Run duration is your call, but push yourself.
8C) SPEED: Run for ten seconds, then jog for 90. 1–3 sets of 6–8 reps (add one set and rep each cycle).

INTENSIVE
8D) 15/15/15: Jog for 15 seconds, run for 15, then sprint for 15.
4 reps; add 2 each week.
8E) HILL/STAIRS: Run 100 yards up a moderately sloped hill, or run up some stairs for 15 seconds. Walk down. Hill: 6–8 reps; stairs: 10.