Until you get there you can start practicing these 5 exercises.

Fitness magazines will tell you that you can get there (the picture above) within 30 days... I have tried and it took me about 5-6 months of hard work and dedication not only in the gym but also and essentially in the kitchen to see my 6 pack finally coming out.
Some people are genetic freaks and could eat pizza all day and still look very decent. But for the most part regular people like you and I have to be very focused and train a very long time and eat a lot of very healthy foods to become like the stud in the picture above.

So here is what you can do to start building your core... as it is essential for correct posture and correct movement.

1. Plank

The good all plank is the basic, if the exercise is too hard on your feet, place a pillow under your knee and Plank from your knee. Hold for 10-60sec depending on your level of fitness. The plank is the most basic, but most efficient exercise to get your core to fire!

2. Deadbug

Another great exercise for beginner as you are taking gravity off the equation. Bring your knees at 90 degrees over the hips and your arms straight up in the air. Lower 1 arm over head while maintaining the other arm up and lower the opposite leg down to 3 inches above the floor, making sure your lower back stays in contact with the floor. Come back to the initial position and switch the sides of arm and leg lowering.

3.Supine leg rotation

This will target the side of your abs aka the Obliques (internal and external) are responsible to hold your body straight up and are important to work even if they are not part of the 6 pack they are part of the pack that will make you strong in any lateral and rotational movement (Golf, Baseball, overhead throws sports etc...)

4. Side Plank

Also a great exercise to strengthen your obliques but also your transverse abdominus (deep layer of your ab wall)

5. Standing cable or band hold

Probably the most challenging yet the most easy looking exercise in the list. Stand feet shoulder width appart, externally rotate your knees, squeeze your glutes, place the handle right at your sternum. Shoulders are back and down. Slowly extend your arms out until they are fully extended. If you start feeling this exercise is your lower back I suggest you lower the weight and really focus on tucking your tail under (Posterior pelvic tilt will activate your butt and your transverse abdominus which will reciprocally inhibit your lower back to fire)