Here is a total body weight workout that takes less than 15 minutes. It's for days when you're unmotivated, sleep deprived, late for work, out of town, have a house full of in-laws, the gym is closed, or there's a natural disaster. In other words, days when you fully intend to skip your workout. Do this instead. You'll feel better, and probably eat better.

Requirements:

a pair of dumbbells

a mat

a chair

Choose the pair of dumbbells based on what's challenging for biceps curls. You'll use them for the whole workout. For me, 25 pounders work nicely. There's no rest between any of these exercises. That's partially to keep your heart rate up, and partially because you're trying to get this over with ASAP.

Push-Ups (Chest) - Full military push-ups to failure, then drop to your knees and go to failure again. 

Bent Over Rows (Back) - Bend at the waist (don't lock your knees), back flat, head up, and row. Do both arms at once, elbows close to your body. Really concentrate on pinching your shoulder blades together at the top. Do it until the muscle is really fatigued, about 20 reps.

Stationary Lunges (Quads/Glutes) - Stationary because stabilizing yourself will force you to use your muscles differently. Slow stationary lunges work your whole leg, but especially quads and glutes. Do 15-20 on one leg, then switch and repeat.

Stiff Legged Deadlift (Hamstrings/Glutes) - Keep your back flat, your head up, your hands very close to your legs, and really feel the stretch and contraction in your hamstrings. Do 15-20 reps.

Calf Raises (Calves) - Hold the dumbbells at your sides, raise up on your toes, lower back down. Do 15-20 reps.

Shoulder Presses (Shoulders) - Hold the dumbbells at shoulder level and press them overhead. You're using a weight that should be challenging for your upper body, so on this one you may only get 8-12 reps.

Biceps Curls (Biceps) - Again, this weight will be heavy for your upper body. You may only get 8-12 reps. If curling them together is killing you, alternate one arm at a time to a count of 20.

Triceps Dips (Triceps/Delts) - Sit on the edge of a sturdy chair or bench, grip the edge, put your feet on the floor a couple feet in front of you, dip your butt toward the floor and use your triceps to push yourself back up. You can make it less challenging by keeping your knees bent (whole foot on the floor), or more challenging by keeping your legs straight (only heels on the floor).

Bicycle Crunches (Abs) - Lie on your mat, hands behind your head, legs up, knees bent. Alternate bringing together your left knee and your right elbow, then your right knee and your left elbow. When one leg comes in, the other one straightens out (parallel to the floor) like you're pedaling a bike. The movement is slow and controlled. Focus on really contracting your abs at the top of each movement. Don't pull on your neck. Do 100 reps.

I was going to try to track down pictures or demonstrations for each exercise, but they're pretty basic moves. If you have any questions about how to do something, just e-mail me.