When you sit down to eat; does it cost you any money to say, "I’m eating l’shaim shamayim (for the sake of Heaven)"? "I’m eating to serve Hashem"? That’s what the Shulchan Aruch says you should do: say, I’m eating in order to make my body healthy ... so I should be able to serve Hashem.
You can say it too; say it outloud: "I’m eating in order to have koach (strength) to serve you Hashem!" That’s a tremendous achievement. — Eating In Service of Hashem (#851)