1. To make oneself physically or mentally stronger; to build up one's strength or resilience
She decided to strengthen herself by exercising regularly and eating healthy.
Ela decidiu fortalecer-se exercitando-se regularmente e comendo de forma saudável.
2. To increase one's confidence, willpower, or emotional resilience
He strengthened himself emotionally to face the challenges ahead.
Ele fortaleceu-se emocionalmente para enfrentar os desafios à frente.