1 Corinthians 9:26

²⁴ Know ye not that they which run in a race run all, but one receiveth the prize? So run, that ye may obtain.

²⁵ And every man that striveth for the mastery is temperate in all things. Now they do it to obtain a corruptible crown; but we an incorruptible.

I therefore so run, not as uncertainly; so fight I, not as one that beateth the air:

²⁷ But I keep under my body, and bring it into subjection: lest that by any means, when I have preached to others, I myself should be a castaway.

Do read the surrounding verses too, because the context often says more than a single verse.

Compare

BSB: Therefore I do not run aimlessly; I do not fight like I am beating the air.
KJV: I therefore so run, not as uncertainly; so fight I, not as one that beateth the air:
WEB: I therefore run like that, not aimlessly. I fight like that, not beating the air,
ASV: I therefore so run, as not uncertainly; so fight I, as not beating the air:
DARBY: *I* therefore thus run, as not uncertainly; so I combat, as not beating the air.
BLB: Therefore I run thus, not as aimlessly; I fight thus, not as beating the air.

ÅB: Jeg løper da ikke som på det uvisse; jeg fekter ikke som en som slår i været;
OTB: Derfor løper jeg ikke uten mål; heller ikke slår jeg i luften som en bokser.
B1930: Jeg løper da ikke som på det uvisse; jeg fekter ikke som en som slår i været;

2 Timothy 2:5
And if a man also strive for masteries, yet is he not crowned, except he strive lawfully.
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2 Peter 1:10
Wherefore the rather, brethren, give diligence to make your calling and election sure: for if ye do these things, ye shall never fall:
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Philippians 1:21
For to me to live is Christ, and to die is gain.
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Colossians 1:29
Whereunto I also labour, striving according to his working, which worketh in me mightily.
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2 Timothy 1:12
For the which cause I also suffer these things: nevertheless I am not ashamed: for I know whom I have believed, and am persuaded that he is able to keep that which I have committed unto him against that day.
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Luke 13:24
Strive to enter in at the strait gate: for many, I say unto you, will seek to enter in, and shall not be able.
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1 Peter 5:1
The elders which are among you I exhort, who am also an elder, and a witness of the sufferings of Christ, and also a partaker of the glory that shall be revealed:
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Ephesians 6:12
For we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high places.
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