Good Ol Fashioned sit ups.

4×25 sit ups, with 1 minute rest between. For added challenge, add hand weights but keep them by chest, don't use them to propel yourself!

Build a house!

If you're not familiar with this one, here you go...

Start standing with your feet at a comfortable distance apart. Bend down as if to touch your toes and walk your hands out in front of you past push-up position. Walk your feet to your hands. This is one rep.

Repeat 30 times. Enjoy!

Or not.

Whatever.

The Marine Corps made this one almost impossible for me.

So in honor of me, try it.

I'm BAAAACK. Yes, friends, I made it through boot camp. Semper Fidelis. Now, for the exercise. Kettle ball squats. Have at them. 3 X 30. Knock yourself out. Not literally though.

Monkey Fuckers

Learned this one at PT today.
Stand with your feet shoulder width apart, grab behind your ankles (thumbs on the outside of your leg).
come down into a 90 degree angle with your knees, almost as if you were about to sit into a chair. (Still holding your ankles) extend your legs until they are straight, still holding your ankles. Repeat this for 2 minutes.
Sprint for 45 seconds.
3 times.

Plank

This is actually a good warm up activity.

Hold for 60 seconds.

Do 4 repetitions.

Fartlek

Warm up for this by walking for three minutes, jogging for five, and finishing with six accelerations (of about 80 yards) to get your body ready for a faster pace.

Block Party: 
In your city, neighborhood, or office park, use blocks as your "track." You can go around the block or do an out-and-back. Start at a slow pace for five to 10 steps, then gradually increase the pace for 20 to 50 steps, then run at race pace (but not all out) for one full block. Start with two or three fartlek segments and build to six. Walk for one or two minutes between each faster section. 

Running Landmark: 
Pick a telephone pole, mailbox, stop sign, or anything up ahead and run to it. You can choose one item (all telephone poles, for example) or multiple landmarks to create varying lengths of speed segments. On each segment, gradually pick up the pace until you're running fast but not all out. For the last 20 steps, hold the pace, but focus on relaxing your body and allowing momentum to take over. Walk or jog for half the distance of your repeat, then spot your next landmark and take off again. Continue for a total of 10 to 15 minutes, before running an easy five to 10 minutes to cool down.

Oblique Crunches

**Stretch, Warm Up**
Lay on the deck on your back, feet on the deck and legs bent at a 90 degree angle.
Twist your legs to the right so that they are on top of each other.
With your arms across your chest, do a crunch towards the overhead.
Do 3 sets of 15 on both sides.