Only by thinking of danger in peacetime can you prevent trouble before it arises.
Tips
history
From 《左传·襄公十一年》: 居安思危,思则有备,有备无患 'think of danger while at peace; such thought brings preparation, and preparation avoids disaster.' Quoted for millennia as a classic of strategic thought.
usage
Apostrophe needed before 安 (a-initial syllable) under Hanyu Pinyin rules: jū'ān not jūān. Very common in political and business speech.