John Chrysostom — as excerpted in the Catena Aurea on Matthew 7:13-14

“But seeing He declares below, My yoke is pleasant, and my burden light, how is it that He says here that the way is strait and narrow? Even here He teaches that it is light and pleasant; for here is a way and a gate as that other, which is called the wide and broad, has also a way and a gate. Of these nothing is to remain; but all pass away. But to pass through toil and sweat, and to arrive at a good end, namely life, is sufficient solace to those who undergo these struggles. For if sailors can make light of storms and soldiers of wounds in hope of perishable rewards, much more when Heaven lies before, and rewards immortal, will none look to the impending dangers. Moreover the very circumstance that He calls it strait contributes to make it easy; by this He warned them to be always watching; this the Lord speaks to rouse our desires. He who strives in a combat, if he sees the prince admiring the efforts of the combatants, gets greater heart. Let us not therefore be sad when many sorrows befal us here, for the way is strait, but not the city; therefore neither need we look for rest here, nor expect any thing of sorrow there. When He says, Few there be that find it, He points to the sluggishness of the many, and instructs His hearers not to look to the prosperity of the many, but to the toils of the few.”