Since I was in the Marines I am all too familiar with these "fartlek courses" as they are called in the military. A standard USMC fartlek will consist of usually a 1/2 mile trail with:
Ropes, incline leg lifts, incline push ups, barbells, dip bars, push up and crunch station, step ups (w/ ammo cans filled with lead), pull up bars, etc.
You basically just run around in circles hitting different stations for like 30 seconds a pop.
Civilian side you obviously have to use more stationary features such as pull ups, incline push ups, steps, and incline leg lift/crunch boards.