"Work hard to go through the narrow doorway." This is part of a metaphor about God's kingdom . In this metaphor, God's kingdom is represented by a house. Jesus was speaking to a group of people. So the "you" implied in this command is plural. (See: [[rc://en/ta/man/translate/figs-metaphor]], [[rc://en/tw/dict/bible/kt/kingdomofgod]], [[rc://en/ta/man/translate/figs-you]])
Becoming part of the kingdom is represented by entering the narrow door. The fact that the door is narrow implies that only a few people at a time can go through it. Translate it in a way to keep this restrictive meaning. (See: [[rc://en/ta/man/translate/figs-explicit]])