Creating a workout plan to develop defined abs using only bodyweight exercises requires a combination of strength training, cardio, and proper nutrition. Remember that achieving defined abs also depends on reducing body fat, so incorporating cardio and maintaining a balanced diet is crucial. Here’s a 12-week exercise plan to help you achieve defined abs:

Weeks 1-4: Building a Solid Foundation Frequency: 3-4 days per week

Day 1: Upper Body and Core

1. Push-Ups: 3 sets of 10-12 reps
2. Planks: 3 sets of 30 seconds
3. Bicycle Crunches: 3 sets of 12 reps per side

Day 2: Lower Body and Cardio

1. Squats: 3 sets of 12 reps
2. Lunges: 3 sets of 12 reps per leg
3. Jumping Jacks: 3 sets of 30 seconds

Day 3: Rest or Active Recovery (light stretching, yoga)

Day 4: Full-Body Workout

1. Burpees: 3 sets of 10 reps
2. Russian Twists: 3 sets of 12 reps per side
3. Mountain Climbers: 3 sets of 30 seconds

Day 5: Cardio and Core

1. Running or brisk walking: 20-30 minutes
2. Planks: 3 sets of 30 seconds
3. Leg Raises: 3 sets of 12 reps

Day 6: Rest or Active Recovery

Day 7: Rest

Weeks 5-8: Increasing Intensity Frequency: 4-5 days per week

During these weeks, you should aim to increase the intensity of your workouts by either adding more repetitions, sets, or incorporating more challenging variations of bodyweight exercises.

Weeks 9-12: Shaping and Defining Frequency: 5-6 days per week

In these final weeks, you’ll increase the frequency of your workouts and incorporate advanced exercises to further shape and define your abs.

Day 1: Upper Body and Core

1. Diamond Push-Ups: 3 sets of 10-12 reps
2. Planks with Leg Lifts: 3 sets of 30 seconds
3. Hanging Leg Raises: 3 sets of 10 reps

Day 2: Lower Body and Cardio

1. Pistol Squats (single-leg squats): 3 sets of 8 reps per leg
2. Jump Squats: 3 sets of 12 reps
3. High Knees: 3 sets of 30 seconds

Day 3: Cardio and Core

1. Running or high-intensity interval training (HIIT): 20-30 minutes
2. Side Planks: 3 sets of 30 seconds per side
3. Dragon Flags (advanced): 3 sets of 8 reps

Day 4: Full-Body Workout

1. Burpee Variations: 3 sets of 10 reps
2. Russian Twist with Medicine Ball: 3 sets of 12 reps per side
3. Spider-Man Push-Ups: 3 sets of 10 reps per side

Day 5: Cardio and Core

1. Jump Rope: 20-30 minutes
2. Hanging Leg Raises with Twist: 3 sets of 10 reps per side
3. Plank to Push-Up: 3 sets of 10 reps per side

Day 6: Rest or Active Recovery

Day 7: Rest

Remember that diet plays a crucial role in revealing your abs. Consume a balanced diet with plenty of protein, healthy fats, and complex carbohydrates while maintaining a caloric deficit to reduce body fat. Stay consistent, stay hydrated, and get enough sleep to support your fitness journey. Consult with a fitness professional if you have any health concerns or specific goals in mind.