lunges

Lunges are another awesome exercise for toning & strengthening your legs, butt, and core. They're portable (can be done anywhere) and deceptively easy (they seem easy, at least to start with, but then your legs & butt will be very sore the next day!) They're also a simple, straight-forward exercise - just lunge forward, and then back up, first with one foot and then with the other.

For more information, Shape magazine has a nice article on how to do a proper lunge.

Variations:

• Standard lunge - feet shoulder width apart; arms at your side or on your hips. Step (lunge) forward with one foot, slowly lower your body, then push off your front foot and return to your starting position. You can either do reps with one leg at a time, or you can alternate legs. Increase the difficulty by holding weights.
• Walking lunge - instead of returning to the starting position, you take another lunge forward with the opposite leg, walking yourself across the room.
• Reverse lunge - same mechanics, but you step backwards, so the leg that doesn't move is the one which gets the workout.
• Side lunge (Angle lunge) - step your leg sideways, or at a 45 degree angle. 

Here's a video from LizYArtur demonstrating proper form:

Legal Disclaimer (don't blame me).

Warning - I am NOT a licensed physical trainer, therapist, nutritionist, or a doctor.  I am a regular guy who just happens to love exercise and fitness.

Exercise can be dangerous if done incorrectly or in excess.  I can't see you, and you can't see me, to know if you're doing an exercise incorrectly, which could lead to injury.

Please Please Please seek help / advice / counsel from a local professional before starting a new program, or before doing an exercise you're unfamiliar with.  This information is intended as a guide to point you in the right direction.  If you aren't familiar with the exercises described herein, I highly recommend seeking professional advice before trying them.