The idiomatic expression "to feel stronger" means to become more confident, powerful or capable. It implies that a person is experiencing an increase in physical strength, emotional resilience, mental clarity, or any other type of personal power. This can be due to various factors such as exercise, proper nutrition, rest, therapy, medication, or simply gaining experience and mastery over something. The phrase is often used figuratively when describing a person's emotional state or their ability to overcome challenges in life.