This core-focused workout is designed to strengthen and tone your midsection using a series of bodyweight exercises. Each exercise is crafted to target different areas of your core, ensuring a well-rounded routine that promotes both strength and muscular endurance.

Start with the 'Crunch (arms straight)', performing 4 sets of 15 reps. Lie on your back, legs bent at the knees, and arms extended straight towards your knees. Crunch upwards, lifting your head and shoulders off the ground while keeping your arms straight. This variation intensifies the engagement of the upper abdominals.

Next, move to 'Alternate Oblique Crunches', which involve 4 sets of 15 reps per side. Start by lying flat on your back with your hands behind your head. Bring one knee towards the chest and rotate your opposite elbow towards the raised knee, alternating sides. This exercise targets the oblique muscles and enhances rotational strength.

Continue with 'Alternate Leg Raises', executing 4 sets of 15 reps per leg. Lie back on a mat or flat surface, hands at your sides or under your lower back for support. Alternately raise each leg to a 90-degree angle and then slowly lower it back down, keeping your core engaged and your lower back pressed to the floor.

Conclude your session with the 'Body Saw Plank', performing 4 sets of 15 reps. Assume a plank position on your elbows and toes, keeping your body in a straight line. Rock forward and back on your toes, engaging your core to maintain stability. This dynamic movement helps to increase core endurance and strength.

Together, these exercises provide a comprehensive core workout that not only helps strengthen the abs and obliques but also improves overall body stability. Consistency with this routine will lead to noticeable improvements in core strength and muscular definition.