The upper abdominal curl is a great exercise for building stomach and core strength. It may be a bit difficult at first, however you should persevere with this because as your abdominal strength increases the shaking will slow down.
To start, Lay on your back with knees bent, feet flat on the floor and your back relaxed. Interlace your fingers behind your neck. Take a deep breath
While exhaling, pull your stomach in toward your spine and slowly lift your head (being careful not to lift with your hands behind your neck), tuck your neck into your chest. Slowly roll your torso up to a position where your shoulders are just above the mat.
Inhale and hold this position.
While exhaling, slowly lower yourself back to the starting position.
Repeat this 10 times.