You need first to master habits development, then develop several habits in a few specific areas and that will make a great bridgehead for self-discipline mastery.
You can do many different kinds of self-discipline exercises, but until you habitualize them, they will be of little value. The moment your attention and focus will wither, your self-discipline will disappear with them.
Habits constitute who you are. Yu need to make self-discipline a part of yourself to master it. You need relevant habits.
1. Speech habits.
Governing your tongue is governing yourself. If you blurt out something without thinking, it’s a sign that self-discipline is foreign for you.
You need to get a grip over your self-talk. It will make easier to manage your speech patterns when interacting with others, but it will also become a significant introduction to govern your mind.
Habits that will help:
-meditation; it makes you self-aware especially about your inner chatter
-free-style journaling; it reveals your internal voice and your speech patterns
-introducing specific vocabulary to your utterances; try using a new word 10 times in one day; try saying 100 times a day “thank you” or “yes”; track how many times you say a specific curse and in the following days eliminate it from your vocabulary
-silence; try to not say a word for a whole day or its part (e.g. two hours normally full of social interactions)
2. Mindset habits.
Your language affects your way of thinking. Your self-talk shapes your beliefs and philosophies. Learn how to think differently and it will contribute to the mastery of self.
If your beliefs are lousy, your self-discipline is loose. For example a belief that “a bit of junk food from time to time is not so harmful” can affect your self-discipline when you decide if you should eat another snack or drink one more can of soda. Beliefs replacement and reshaping your mindset can be a gruesome process. We aren’t used to changing our way of thinking.
-meditation; applicable here as well; being present in the moment with no thoughts whatsoever has a quality of challenging all your beliefs
-affirmations; it introduces new speaking patterns into your self-talk
-cultivating gratitude; it makes your whole thinking more positive, I never met a single person who couldn’t have used more positivity in their thinking
-changing your data sources; start following a new blogger, stop watching TV, start reading books every day- it all will shift your thinking
-meeting new people; simply decide what qualities and way of thinking you would like to adopt and start seeking people who already have them, you will absorb them via social osmosis even without your conscious effort (but being intentional can speed up this process significantly)
3. Bodily habits.
A lot of lack of discipline come from giving up to simple temptations: to sleep in, to indulge with sweet or greasy or salty snacks, to quiet our nerves with cigarettes and so on. It has a ripple effect on your self-discipline as a whole. If you learn how to crumb those temptations, you will improve in other areas, like time management or studying.
-exercise; I cannot emphasize enough the importance of this habit; it’s a keystone habit, it will affect everything in your life; it will increase your willpower and energy levels
-change your diet; introduce new, or more, kind of foods you know are healthy and useful for you, like eating one vegetable a day
-eliminate some harmful foods from your diet; e.g. abstain from sweets for one day, one week, for ever