Most Helpful Girl
I have a six pack.. I know, not a good look on a girl!
For gymnastics I needed good core strength so I set about doing as many sit ups as I could in a minute. I did this every day and can now do 70 sit ups in 60 seconds :)
So.. For a minute's worth of exercise a day I got myself a six pack..
I am naturally thin though, so it might not work for everyone, but it's definitely worth a try. And it does wonders for your core strength and stamina!