To Know God —— By reading the Bible daily, reading a daily devotional, going to C.C.D. or Life-Nights, attending Bible studies, etc.
To Love God —— By going to Mass daily or weekly, by praying constantly, spending time in adoration, by sharing your faith (testimony) with other people, etc.
To Serve God —- By helping in Mass, by doing chores at home without being told, by helping the needy without expecting pay, works of Mercy, etc.
God put us in the world to know, to love, and to serve him, and so to come to paradise. (CCC 1721)
In order to serve God with grateful hearts; we must first need to know about Him. As we know more about Him, the LOVE starts to grow and once we start loving Him our being can not stop serving Him. The more we serve Him, the more we love Him and know Him and that circle those not stop which ends up in saint hood.