Kilian Markert, Speaker and Coach for Inner Transformation
Because you’re relying on willpower.
What I’ve come to realize after working with hundreds of people that were lacking self-discipline is that they did not have any reliable structure in their days that made it easy to take action, but rather were relying on willpower.
Willpower is somewhat like a muscle, a source of energy that depletes over time. Relying only on willpower could serve in the very beginning when motivation is still very high. Whatever goal you have set for yourself, you are excited to give it a shot and eagerly do the first steps.
Over time, however, your willpower will decrease. This depletion can be seen over the course of several days and weeks, but also in a single day, as your willpower starts off high in the morning and declines towards the evening.
At this point it will be very difficult to pack your bag for the gym, to resist that delicious pizza around the corner, or to finish that book instead of wasting time on social media.
You then wonder why you don’t have any self-discipline.
So both motivation and willpower are actually rather low ranking traits on the scale of consistency and productivity.
Let’s look at the four levels:
Willpower/Motivation: As described, having good levels of willpower can be useful to make yourself do something and overcome laziness. However, just like motivation, willpower is unreliable, so this is actually the lowest level of productivity and consistency.
Discipline: Discipline implies that you have to bring up a certain degree of willpower to overcome laziness. It is better than sheer willpower alone, because you regularly bring up that willpower and get used to doing it, especially if you don’t feel like it. However, it’s not reliable either, since on some days you manage to discipline yourself, on others you don’t.
Habits: Habits are the cornerstone of consistency. You shift from conscious effort and willpower to implementing habits that take over and run on autopilot. The key is to implement habits by designing your environment and it will be easier to actually stick to them and make them a part of your day.
Identity: This is the ultimate level of consistency. It is an evolution of habits. Once you are consistent with your habit for a long period of time, these habits will turn into your identity. It will not be a habit for you to e.g. go to the gym, you simply will go to the gym no matter what because you are a person who goes to the gym.
At the last stage, there will be no questioning, no laziness, you literally just do it. You would have to use willpower to not do it.
This is where you want to be. Whatever goal you have. Don’t think of the result, but rather the kind of person you have to become and the tiny steps that are needed to get there.
Reading some pages, doing some minutes of exercise, cooking a healthy meal yourself… taking small steps in the right direction on a daily basis establishes lasting habits that will ultimately shape your identity.
What is the first step to get there?
Choose a keystone habits and make it stick.
A keystone habit is a habit that once established can have a ripple effect, whose benefits expand to other areas of your life and thus over time improve it as a whole.
Charles Duhigg describes them in his book “The Power of Habit” as, “small changes or habits that people introduce into their routines that unintentionally carry over into other aspects of their lives.”
What are examples of keystone habits?
One example is exercise. Regular work-outs have several side effects. You develop a better posture and feel better, which is easily noticed by your surroundings and can help you in your dating life. It also makes you take care of your nutrition and how you treat your body. It increases self-discipline and thus affects your progress on difficult tasks and so on.
You will then notice how it will influence other areas of your life and allow you to progress in these areas.
How do I actually stick to my habits?
By making it easy to stick to them through intelligent design of your environment. 
A good example of how to use Environmental Design is your phone. The first thing many people do after waking up is to reach for their smartphone and check messages, e-mails or notifications from social media. This sets you in a reactive state and will prevent you from focusing on your true priorities.
Therefore, before going to bed, intelligently design your environment.
Put your phone in airplane mode and place it somewhere impossible to reach from your bed. Prepare your to-do list with the 5 most important things you want to achieve the following day and place it somewhere you can see it as soon as you wake up.
After waking up, you can directly focus on the tasks that lie ahead. Should you still instinctively reach for your phone, there will be no distractions available due to the airplane mode.
This will allow you to start your days in a productive instead of reactive state. This is one of the most important aspects of productivity, because remember:
“If you commit to nothing, you’ll be distracted by everything”
To summarize, discipline and willpower are not reliable. Focus on implementing daily habits which make taking action inevitable and automatic.
Hope that helps,