You're not into wasting your time, but luckily, you don't need to devote hours at the gym for a strong core. You just need to do the most effective ab-strengthening moves, and this four-minute workout has them all! You'll target your upper, middle, and lower abs, as well as your obliques.
What you'll need: floor space, a pull-up bar, and a medicine ball
Perform this workout once a day for one week and see how you feel! If you're not sure how to do each movement, see the descriptions ahead.