From your triceps press position, bend your left elbow underneath your shoulder, propping your upper body up. Extend both legs out straight under your hips and cross your right leg over and slightly in front of the left, pressing the inside edge of your right foot into the floor. Extend your right arm straight up towards the ceiling and lift your body off the floor, pressing up through the left side of your body, into a side plank.
Next, take your right arm and sweep it under and behind your body, reaching underneath the left side of your ribcage. As you reach through, exhale and squeeze your abdominals in tighter and allow your hips and feet to twist naturally into the movement as you reach. Then, open your right arm back up towards the ceiling, returning to your starting side plank pose. That's one rep. Try for 10 reps on the left elbow, then do 10 on the right, before going back to your triceps press [3A].
Form tip: Be sure to keep your bottom elbow directly underneath your shoulder during this move. If you feel a lot of strain in your shoulder, you may need to pull your elbow in closer to your body and focus more on lifting through the side of your torso, not your arm.
Try to complete 2 full sets, moving quickly back and forth between the triceps press and the side plank, before moving on to the next (and final) set.