Paused Leg Extensions
A lot of people like to get on the leg extension machines and passively text their Bff's until they grow bored sitting there.
STOP! Put more focus into what you're doing! If you need help, then give this variation a try.
Make sure you secure yourself tight in your seat, your back flat against the pad. Retract your scapula and stabilize your torso. Notice my arms are flexed, that's to keep the lift focused on my quads - don't let yourself swing the weights up and down.
You don't need to pause forever, just long enough to really squeeze your quad at the top of the movement. Watch out, this burns!!!