Okay, look ... your tummy muscles serve one purpose ...
... to pull your thighs and torso closer together.
So, the basic tummy exercises involve lifting your body up to your legs (sit ups and crunches)
... or lifting your legs up to your body (leg raises, etc).
So lets eliminate gym work, and think what you might do in the kitchen, while waiting for the kettle to boil.
Put your hand out in front of you, as if you were patting a big dog on the head.
Bring your left knee up to touch your right hand.
Then swap, and bring your right knee up to touch your left hand.
Do it repeatedly.
By the time the kettle has boiled, your tummy will have had a pretty serious workout.
Then, sit at your desk.
Press your elbols down on to the desk.
Lift your feet about 6" off the ground ... and hold.
You will feel it in your tummy.
Do these exercises a lot.
Build up on you "knee raises" until you can do it for the duration of the Jeremy Kyle Show.
By the time you go on your summer holiday, you will have abs of steel !!!
J xxx