Sprints: 20 min
Warm up at your 5K pace for 2 minutes.
Alternate Sprint/Rest for 20 minutes
Sprint for 1 minute: Increase the treadmill to a sprinting speed (for me, it's about speed 9 on a Lifetime Fitness Treadmill) The speed should get your heart rate up to 180 beats/minutes by the end of 1 minute.
Rest: Carefully jump off the mill. It's easiest if you hold on to the handbars and land your feet to the outside of the moving belt. Rest until your heart rate reaches 140 beats/minutes.
Circuit 1: 3 Sets
Bench Press: 10 reps (I did 50 lbs) * it's always good to have a spotter. However, we don't all have the luxury of working out with someone else. Just make sure there's enough other gym-goers around. In case you get pinned, someone can help you out!
E-Z bar curl: 10 reps (30 lbs) see video here.
Skull Crushers: 10 reps (30 lbs) see video here. * these are easier with an "E-Z" bar, which is basically a straight barbell but in the middle of the bar is zig-zag for easier gripping.
Circuit 2: 3 Sets
Pull Ups: 10 reps (55 lb counter balance) * if you haven't worked up to unaided pull-ups, add a counterbalance weight enough so you still feel your muscles worked by the 3rd or 4th rep, and muscles are tired by the 8th rep.
Dips: 10 reps (55 lb counter balance) * same as the pull-ups, use a counterbalance if you need to.
Push Ups: 10 reps
NOTE: I'm not a certified Personal Trainer. Try all of these workouts at your own risk.