Upon reaching the age of puberty, you may pray your five daily prayers because they are wajib and you are worried that if you don’t, you will be punished. You might also pray because you hope that in exchange for your worship, you will go to Jannah and have anything and everything you ever wanted.
But as you grow, you mature. You become more and more aware of Allah’s kindness in showering you with so many blessings you can’t even count them. Sight, hearing, strength, life, time, parents, education ... the unending list of God’s gifts overwhelms you with gratitude.
You realise how much you need God’s mercy for everything – without it, you couldn’t even flare your nostrils to breathe or lift your eyelids to open your eyes to see! Every raindrop, bird, flower – everything – is from Him; so how can you not praise and prostrate before Him in worship?!