Thanks for writing in.
Its great that you are in great shape but your stomach probably looks like that due to bloating
or due to faulty eating habits.
For both these conditions, the following will help:
a. Eat small meals at regular meals
b. Take plenty of water, 2-3 litres in a day
c. Have an early dinner
d. Have plenty of fiber in the form of fresh fruits and vegetables
e. Apart from the situps and the pushups, you should be doing atleast 50 minutes of cardiovascular exercise every day.
f. Have a source of a monounsaturated fatty acid like walnuts and avocados in each meal.
Hope this helps.