Just as you must exercise to make your muscles grow and remain strong, you have to exercise your faith to grow and strengthen it. Simply accepting Jesus into your heart and then moving on with your life as if nothing else has changed will not help you grow in your relationship with God.
Spiritual growth comes through daily communication with him through prayer and the reading of his Word. Don’t just say memorized prayers, but talk with God by giving him praise and thanks, and then sharing with him whatever is on your heart. Take a few moments to be still and listen for him to speak to you. More growth happens as you regularly fellowship with other believers through church attendance, Bible studies, and/or small group activities.
You will grow in your faith if you involve God in every aspect of your life and take everything to him in prayer!
Colossians 2:6 (TPT) - “In the same way you received Jesus our Lord and Messiah by faith, continue your journey of faith, progressing further into your union with him!”