This is an excellent exercise for flattening your tummy and strengthening your legs and lower back muscles.
1 Lie flat on your back, arms at your sides.
2 Raise one leg until it is as near 90 from the floor as it will comfortably go. Lower it. Repeat with the other leg.
If you do this very fast, it is quite easy. What you have to work towards is raising your leg as slowly as possible.
3 Repeat the exercise, this time pausing for a count of five when your leg reaches an angle of 45%
4 Now repear the whole exercise, raising both legs together.
When your stomach muscles have become strong enough to do this without strain (and not until then) add this next stage to the exercise.
5 Now sweep them apart and together again, letting one leg cross over the other; sweep them apart and together, letting the other leg cross over. Make the movement as flowing and rhythmical as you can.
Dot this exercise just once or twice at first, increasing the number of times gradually as your muscles get stronger.