Isabel was a young girl with a bright smile and curious eyes. One day, as she was walking in the forest, she stumbled upon a tiny fairy that was sitting on a mushroom. The fairy introduced herself as Ondina, and Isabel was amazed by her glittering wings and her soothing voice. Ondina asked Isabel if she had a wish, and Isabel quickly replied that she wanted to be the strongest girl in the world.

Ondina smiled at Isabel's request, but before she granted her wish, she warned her that being strong requires more than just a magical spell. Isabel needed to take care of her body, eat healthy food, and exercise regularly to become truly strong. Isabel nodded eagerly, feeling determined to follow Ondina's advice.

The next day, Isabel woke up early and headed to the grocery store with her mother. She picked out a variety of fruits and vegetables, and asked her mom to buy her some lean meat and eggs. Her mom was surprised by Isabel's unusual request, but she supported her daughter's eagerness to become strong.

Throughout the week, Isabel started to cook healthy meals for herself. She made some delicious salads with tomatoes, cucumbers, and carrots, and added some grilled chicken on top. She also learned how to make omelets with spinach and feta cheese for breakfast, and started to drink fresh juices made with oranges, grapes, and berries.

Isabel also started to exercise every day. She went for a run in the park, did some pushups and squats at home, and even joined a local gymnastics class. She loved the feeling of her muscles working, and she was proud of herself for making the effort to become stronger.

As the weeks went by, Isabel's body started to change. Her arms and legs became more toned, and her belly flattened. She was amazed by her newfound strength, and she couldn't believe how good it felt to be healthy and fit.

One day, as she was walking in the forest again, Isabel met Ondina once more. Ondina smiled at her and asked her how she was doing. Isabel grinned and flexed her bicep, showing off her muscles. Ondina nodded approvingly, and told Isabel that she had truly become the strongest girl in the world.

Isabel felt a surge of happiness and pride. She thanked Ondina for granting her wish and for showing her how to become strong. Ondina smiled at her and said that the real magic was within her all along - she only needed a little help to unleash it.

From that day on, Isabel continued to take care of her body and mind. She knew that being strong was not just about lifting weights or running fast, but also about being kind, brave, and determined. She felt grateful for the lessons she had learned, and looked forward to new adventures and challenges.