Well, the First Reading points out a contrast between the two favoured kings of Israel: David and his son Solomon. David was powerful yet he never owned a chariot; he was truly humble and was totally dependent upon God. Solomon, on the other hand, was powerful and intelligent, yet totally dependent upon his many chariots. In the Second Reading, St. Paul captures this contrast beautifully when he talks about dependence on the “flesh” without the “spirit” – a dependence upon self rather than upon God’s assistance.
If you have ever visited the Grand Canyon, you may have taken a ride on the donkey from the rim of the canyon down to the canyon floor. That meek little donkey has only one purpose in life (as far as I know), and that is to help carry the burdens of others - - either you as a passenger, or to back-carry the supplies for others on his back. The message we get from this is: why do it yourself, when you can have help with your burdens?
We learn this lesson from the actions of Jesus himself. He humbly accepted his situation in life, and always trusted totally in his heavenly Father. Jesus tells us the same thing in the Gospel: don’t depend upon yourself, trust in Jesus to help carry your burdens. More importantly, learn to carry your own burdens with His yoke - - he is there to help you, to lighten your burden. That is what Humility is all about, learning to turn humbly to Jesus, acknowledge your need, and accept His help.
Jesus who was All-Powerful did not cling to his power, but became flesh, to offer us his Yoke as our model of holiness. By his own poverty, he gives us the example to follow in our every-day confrontations with trials and burdens. We will never enter the kingdom without humility, because humility is the antidote to sinful Pride.
Also see articles #459, #520 and #2559 in the Catechism of the Catholic Church.