Onyx is a strength workout cut like its namesake stone - layered, dark and dense: 5 slow squats, a 10-count squat hold, 5 regular squats, then 5 slow push-ups, a 10-count plank hold, 5 regular push-ups, finished with a 10-count side plank hold. Two exercises, three tempos each, and a final hold that asks your obliques to sign off on the whole thing.

The structure runs each movement through a complete tempo spectrum, and the order is the point. Slow reps come first, stripping out momentum while your muscles are fresh enough to control every inch of the descent and rise - which is where most of the strength-building tension lives. The hold then freezes you at the hardest point of the movement, converting motion into pure endurance. Only then do you get regular-speed reps, and by that stage normal speed feels like a gift your legs and chest no longer quite deserve. Like the banding in onyx, each layer is distinct but formed under the same pressure. The side plank at the end shifts the load laterally, closing a sagittal-plane workout with a frontal-plane hold so your core finishes what your limbs started.

Take slow squats and slow push-ups at three to four seconds in each direction, keeping the tempo even through the hardest inches rather than rushing them. Hold the squat at working depth, chest proud, weight in your heels. In the plank hold, push the floor away and keep one straight line from head to heels. For the side plank, stack your shoulder directly over your wrist, lift your hips high and reach the top arm skyward - a sagging hip is the only flaw this stone will show.

Onyx forms in layers, slowly, under pressure. So does everything this workout is building.

Make it Harder: Extend all three holds to a 20-count, side plank included.

Make it Easier: Take the push-up block from your knees and drop the side plank to a knee-supported version.