You need aerobic exercises like running or swimming to get rid of belly fat if you have any. Then once you have a flat stomach, then work on ab exercises to achieve your 6 pack. Some ab exercises besides sit-ups/ Crunches are planks, leg lifts, (balancing on your butt with feet not touching the ground). You could also look up "8 min abs" on YouTube. They have good simple workouts, and although some may include sit ups/ crunches, there are many that don't so you could just skip over the ones you don't want to do. Good luck!