A good mix of runs for half-marathon training.

• Two or three aerobic runs, 4--6 miles long, run entirely aerobically.
• One tempo run: 6--10 miles long, run 50% aerobically, 50% harder-than-race-heart-rate.
• One day of speed work (800-meter repeats, or a quarter-mile hill workout), every other week, usually about 5--6 miles total.
• One long run, approximately 80% done aerobically, with the last ~20% at "race heart rate".
• One day of cross-training (a 30--45-minute bike ride).

Check out the run!