1) The purpose of believing in Jesus - have you ever thought about living with Him forever? Or just to help you? (Psalm 68:18; Revelation 21:3)
2) After the two "who shalls" (V1), David made a list of how to be a person to answer it. Are you willing to “[swear] to [your] own hurt and [do] not change” and "[do] these things … [and] never be moved" and stick to this principle for the rest of your life?
3) What kind of people can achieve this? (Psalm 24:3-6)