If someone were to write about you and state that something was your “custom,” what would they mention? “Every morning, his custom is to…” “When she gets to work, her custom is to…” What do other people know to be “customary” for you? 
Is it something you’d like for them to write to the world about?
Like Jesus before him (cf. Luke 4:16), Paul had certain things that were a “custom” for him. Luke announced to the world that Paul’s custom was to go to the gathering of those who feared God in each city and reason with them from the Scriptures (Acts 17:2). That’s what Paul was known to do–by men and by God.
On Sunday mornings, what is your custom? On Sunday nights and Wednesday nights, what is your custom? When your workday is going every which way but right, what is your custom? When no one else is around and will ever know what you do, what is your custom?