1. Push-ups- Max Reps
2. Sit-ups- Max Reps
---- 5 Rounds
3. Then, Run 3 Miles
You should alternate the Push-ups and Sit-ups for 5 rounds, and then start your run. Remember to warm-up and stretch before starting your workout. Do the run at your own pace and try to keep the same pace the whole time for this particular workout. If you are unable to run 3 miles, run as far as you can and walk the rest of the way.
This is pretty simple, but still effective.
Have fun. Good luck, and train hard!