"Au cœur de l'hiver, j'ai finalement appris qu'il y avait en moi un été invincible"

Simplified Meaning:

Even during the toughest and hardest times in life, you can find a strong and happy part inside you that keeps you going. Imagine going through a very cold and harsh winter. No matter how cold it gets outside, inside you, there is always a warm part, like summer, that never goes away. This warm part is your hope, strength, and positivity. For example, think about someone who loses their job and feels very down. At first, they might feel like it's winter in their life—dark and cold. But as they deal with this tough time, they realize they have skills, talents, and a support system from friends and family that help them stay positive. They use this "summer" inside them to stay hopeful and find a new job or even start a new career. This idea shows that no matter how hard things get, you have an inner strength that can help you push through and find better times.