Assisted Sit-up

Sit on the edge of a bench or have someone hold your feet down.

Lie flat on your back with your knees bent and feet flat on the ground.

Place your hands behind your head with your elbows pointing outwards.

Engaging your abs, slowly lift your upper body off the ground, curling forward until your torso is at a 45-degree angle.

Pause for a moment at the top, then slowly lower your upper body back down to the starting position.

Repeat for the desired number of repetitions.

Recruiting larger muscle groups to "help" move the weight instead of isolating Abs — swinging momentum or shifting the torso takes tension off the muscle this exercise is meant to train.

Locking out too fast or letting the elbows drift outward under load — controlling the eccentric (lowering) phase is where most of the muscle-building stimulus happens.

Skipping a warm-up set at lighter load/intensity — even "beginner" exercises benefit from a rehearsal set to groove the movement pattern before working sets.