If you want to make sure that your diet fails, start focusing on all the things you can’t have. No desert for you. Nothing from the candy dish. Can’t have that second helping. All those “no”s will wear your resolve down. It gives what you can’t have more power over you and if this is a weakness already, there is the great temptation to fail.
Rather focus on what you can have. You can have flatter stomach. You can be healthier. You can have more self control. You can fit into your favorite clothes. You can feel better about yourself.
Or you can have that candy bar.
Faith life is not much different. A person can focus on all the desires that they have and the “can’t have that” attitude. No sex outside of marriage. Can’t get drunk. Can’t miss Mass. If you see faith as one giant “can’t”, it will become overbearing, a load too heavy to carry.
Rather focus on what faith gives you. Freedom from the slavery to sin, the freedom to become the best version of yourself. Freedom from the consequences of sin (diseases, unplanned pregnancy, drunk driving accidents, hangovers . . .), sins that have momentary pleasures and lifelong consequences. You can have a deeper relationship with God. You can have better relationships with your loved ones. You don’t have to be angry, secretive, or anxious. And you do not have to be afraid of death.
Or you can walk out of the store knowing they gave you too much change.