People tend to over complicate training abs. Some do too much, some not enough but most often they don’t train them correctly. Below I listed my favorite go to workout for abs and how to do it.
I call this the Quick-Vic. Do this 3x a week at the end of your workout and if done correctly you will notice immediate changes within the first 2 weeks. 
| Exercise | Sets | Reps |
| Roman Chair Sit-ups | 3 | 15×3 |
| Russian Twists | 3 | 15×3 per side |
| Decline Leg Raises | 3 | 15×3 |
Perform the exercises in a tri-set circuit fashion resting only once you completed a set of all 3.
Roman Chair Sit-Ups: lock your legs into a decline bench and either tuck your hands behind your head with elbows flared out or cross arms placing hands on shoulders and perform your sit-up by lifting your torso towards your legs. Squeeze for a count of 1 at the top and reverse slowly to about 8in off the bench and repeat for all 15 reps
Russian Twists: In the same position as the Roman Chair Sit-Ups, simply extend your arms straight out with elbows locked and hands clasped and slowly twist your torso about 45 degrees from the center line, then twist to the other side in the same fashion = 1 rep. Perform all reps to complete the set.
Decline Leg Raise: Lay on a decline bench with head towards the leg top and feet near the ground. Holding onto the leg pad or handle begin lifting your legs (with a slight bend in the knees) up towards your torso. Once your feet are pointing towards the ceiling, elevate your hips/pelvis (anterior pelvic tilt) slightly off the bench to complete the rep. Slowly lower hips back down to bench, then legs back down towards floor. Perform all 15 reps to complete the set. Due to the challenge of these, you may utilize a rest pause technique which entails doing as many as you can on the first go, then rest about 10-15sec, then do as many as you can. Continue in this fashion till you finish all reps
Here is another one of my favorite abs workout. This video by The FIRM is what is my secret weapon on top of the Quick-Vic. Do day 4 on this video, it is absolutely brutal and I recommend trying all 5 days. I guarantee you will notice the difference within a week or 2. Let me know what you think in the comments!