Sit-ups may seem old school. But, when done correctly, they're effective and that's why they've stood the test of time. Late-night infomercials and different workout programs have tried to improve upon the basic sit-up for years. But you don't need any $19.99, plus shipping and handling, tool to get the job done.

Safe and effective sit ups are as simple as ABC ... and D. (Though that darn 'D' makes the whole shtick a lot less catchy.)

• A is for Alignment. Lie on your back with your knees bent. Keep your feet flat on the floor and don't hook them under your couch or anything else. Position the small of your back flat on the floor. With your hands resting lightly on your temples (not behind your head -- pulling can injure you), lift your head, neck and shoulders off the ground.
  
• B is for Body control. When lifting up, make sure your abs are doing the work. Go slowly. Remember to breathe while doing the sit-up.
  
• C is for Consistency. Don't expect a few sit-ups once a month to do the trick. Try doing sit-ups every other day, and remember that quality is better than quantity -- 10-20 with proper form are better (and safer!) than many sloppy ones.
  
• D is for Develop all the abdominal muscles. Traditional sit-ups don't target the lower abdominal muscles and you don't want them to feel left out, do you? Try lying on your back with your knees bent, then bring one knee toward your chest and hold for a few seconds. Bring the other leg up and then slowly lower the first leg, then the second. Repeat on both sides.