It is about knowing God, loving Him, being His friend. It is about communing with Him, being honest, asking questions, getting answers, being you and knowing He loves you just the way you are. It is seeing Him gently smile at your mistakes, knowing you are in process, and you are making progress.
You are growing from an acorn to a tree. He bursts with pride at how strong you are becoming. He loves how you are learning to hear His voice. He delights in how quickly you obey, and how tender and compassionate you are becoming.
Thriving spiritually is growing spiritually, acting like Him. . . loving like Him.
You are thriving spiritually by giving Him your attention.