There are two ways to live and make choices in your life.
1. Based on what you know.
2. Based on what you feel.
When you make the choice to operate based on what you know, then you will succeed in this life.
You know you need to work to pay the bills. You feel like quitting.
You know you have a responsibility to your family. You feel like being irresponsible.
You know eating a balanced meal of protein and vegetables is good for you. You feel like eating half a cheesecake.
When what you know and what you feel are different, discipline is required. Discipline is forming a habit to live by what you know.
It is no different with your life in Christ. The Spirit and the flesh are contrary one to the other (Gal 5:17). The Spirit tells you what to know about who you are in Christ, and your flesh tells you how to feel. Spiritual discipline is needed to live by what you know, instead of how you feel.
Spiritual discipline is not a ritual that brings you closer to God, or an act of devotion that gives you a feeling of spirituality. Spiritual discipline is operating based on what you know of Christ in you.
You know your old man is crucified with Christ (Rom 6:6). You feel his influence every day. Reckon him dead based on what you know.
You know that you are not under the law. You feel its condemnation when you do not keep its holy standards (Rom 7:24).
You know the Spirit of God dwells in you (1 Cor 3:16). You don’t feel his presence.
You know what is God’s will according to the scriptures rightly divided (1 Tim 2:4; 1 Thess 4:3; 1 Thess 5:18). You don’t feel the Spirit leading you. The Spirit is God. You should operate from what you know.
When you make the choice to operate based on what you know, then you will succeed in this life. This takes discipline.
When what you know is Christ in you, then you will succeed in this life and the next (1 Tim 4:7-8). This requires spiritual discipline to live by the knowledge and spiritual understanding gained from God’s word rightly divided (Col 1:9).
Spiritual discipline is not an act you perform. It is forming a habit to live by what you know.