How do I get serious and disciplined

discipline

Examples:

"We [doctors] were amazed by the force with which diabetes sufferers were concerned with one topic in particular: renunciation," says Wolfgang Himmel, head of the general medicine department at Göttingen University Hospital. "Your thinking, your actions, your perception - everything revolves around a moral test: Having to prove that you always behave moderately, always disciplined, always healthy." [Süddeutsche Zeitung, 02.27.2016]

“As long as you work in a disciplined manner for the team and perform well, everything is fine. The only problem is when a player ignores the team. And that's not really the case, "says the 33-year-old [soccer player]. [Die Welt, 09/21/2005]

transferred In contrast to Moscow, which [architecturally] was able to come up with excessive romantic individual objects of Art Nouveau, the »Peterburgskij modern« is rather restrained and disciplined even in its early romantic phase - by an undercooled and controlled emotionality. [Schlögel, Karl: Petersburg. Munich / Vienna: Carl Hanser Verlag 2002, p. 59]

And only those who show that they torment themselves, that they discipline themselves, that they want the washboard abs and the leg muscles can rise to the Olympus of our generation. [Illies, Florian: Generation Golf. Berlin: Argon 2000, p. 89]