27. Discipline is superior to motivation. The former can be trained, the latter is fleeting. You won’t be able to accomplish great things if you’re only relying on motivation.
I have the opposite experience - Discipline is external motivation that is forced on people by raising them, schooling them and training them in the army. It's driven by fear of not living up to expectations of others and disappears as soon as these others stop watching. Such a person is only productive in a team or with regular reporting.
On the contrary inner motivation won't disappear when someone isn't watching and is actually aligned with what makes you happy. It also updates in time to match what makes you happy.
For example if you have a hobby of painting miniatures that you enjoy and then decide to turn it into your only source of income, then you put a lot of performance stress on it. Your motivation gets updated - Stress is subtracted from the joy of the process and the sum might drop below the value of some other activity like watching educating youtube videos that isn't weighed down by expectation of serving as the primary source of income.
If this happens, then approach of discipline is to ignore this change and force yourself to do the thing you don't enjoy because discipline is all about giving up what you want to do what's good for others.
On the other hand the approach of motivation is attentive to this change, this useful signal. You care about your happiness and in order to protect it you can increase your hourly rate, start rejecting uninteresting projects or diversify your income by other sources to alleviate unreasonable expectation of productivity.
The argument that you can't accomplish great things with motivation alone is countered by examples of subjectively great things that I have accomplished by intentionally ignoring external motivation and only following internal motivation.
Admittedly to accomplish your long term goals you need to spend some of your daily supply of attention on reminding yourself how the things you are doing will bring about these long term goals. But that is far better than doing things that you don't want.
One great tool for creating those warnings is Habitica - a free and ad-free productivity app for gamifying your own good and bad habits, regular and one-off tasks and self-rewards.