Lie flat on your back with your knees bent, and put your hands on either side of your head. Lift your feet and draw your right knee in toward your chest while extending your left leg straight out in front of you. At the same time, curl up and twist your upper body to the right, so that your left elbow and right knee nearly touch. Lower back to the floor and repeat on the other side, pulling your left knee in as you twist to the left. Continue alternating for 15 reps on each side.
Start by getting into a pushup position. Bend your elbows and rest your weight onto your forearms instead of your hands. Your body should form a straight line from shoulders to ankles. Engage your core by sucking your belly button into your spine. Avoid putting your chin to your chest by keeping your gaze in front of you. Be sure to keep your hips aligned and don't let your lower back droop. Hold in proper form for 30-45 seconds.
Begin in high plank position with your hands directly under your shoulders. Your body should be in a straight, diagonal line from your head to your heels - no drooping! With your core engaged, bring your right knee forward under your chest with the toes just off the ground. Return to plank position. Switch legs, bringing your left knee forward. Keep alternating legs and pick up the pace until it feels like running in place in a plank position. Repeat for 15 reps on each side, or move at a quick pace (with form intact!) for 30-45 seconds.
Begin by sitting on the floor on one hip and pushing yourself up into this core conquering position. Your shoulder should be stacked over your wrist. Keep your chest and hips square to the same side. You can choose to either stack or stagger your feet for balance. Squeeze your stomach muscles to stay lifted! Hold for 30 seconds, and then repeat on the other side.
First step, find a step so your lower body is at a higher incline than your chest and hands. Get in standard pushup position. Squeeze your inner thighs together to keep your core stable, then push up, keeping your abs tight the whole time. Keep your elbows slightly bent, which will keep your muscles engaged and your joints protected. Repeat for 15 reps.
Take a quick breather, walk it out, and repeat the circuit 2-3 more times.