To stay healthy and non-injured during the cross country season, preventive strengthening is a must.  In addition to the exercises below, I recommend you incorporate some exercises from this site: https://fittoplay.org/sports/running/.  (This is a wonderful site with short instructional videos for not only running, but many other sports as well)

You should aim for completing 15-20 minutes of these stregnthening exercises, 3 times a week.  This is in addition to your running and stretching programs.

Non-Aerobic Strength Exercises

Inch worm

Single leg dead lift

Bird Dog

Superman

Bridge

Single leg bridge lift

Tabletop

Lunges

Star planks

Curb dips

Hip raises (on curb)

Balance on one leg

Aerobic Strength Exercises

Burpees

Mountain climbers

Speed skaters

Squat jumps

Side shuffle

Box jumps

Single leg jumps