"But if your eye is bad, your whole body will be full of darkness. If then the light that is in you is darkness, how great is the darkness!
"No one can serve two masters; for either he will hate the one and love the other, or he will be devoted to one and despise the other. You cannot serve God and wealth."
Matthew 6:22-24 NASB
It is a fact that you cannot focus on two different things at once. If your eyes are focused on one object the rest of the things in a room are not as sharp, and if far enough apart, not even in view.
Jesus uses this to make a point. Just as our eyes in the natural cannot focus on two separate things at the same time, likewise, our focus spiritually cannot be on two objects simultaneously either. That is why He states, "You cannot serve two masters."
God demands our full allegiance, therefore we must look to Him with singleness of purpose. In Hebrews 12:1-2 the Christian life is portrayed as a runner who eliminates everything that hinders him so that he has the endurance to finish the race. Not only do we need to cast of sin and every thing that might slow us down, but our eyes must be fixed firmly upon Jesus.
The NASB 2020 puts it like this,
Looking only at Jesus, the originator and perfecter of the faith, who for the joy set before Him endured the cross, despising the shame, and has sat down at the right hand of the throne of God.
And the Amplified version states,
Looking away [from all that will distract] to Jesus...
The idea is to have a single eye to the glory of God. Our eyes, Spiritually speaking, must be turned away from every distracting thing, and placed on Christ alone. Just like the old hymn reads,
"Turn your eyes upon Jesus.
Look full in his wonderful face.
And the things of earth will grow strangely dim,
In the light of his glory and grace."
Our hearts go out to what we love; what we are devoted to. We are told to set our minds (KJV uses the term affections) on things above.
If then you have been raised up with Christ, keep seeking the things above, where Christ is, seated at the right hand of God.
Set your mind on the things above, not on the things that are on earth.
For you have died and your life is hidden with Christ in God.
This in not merely a mental exercise where we think about heavenly things all day, but a going after these things, drawn by a passion for them, born out of an ultimate passion for Jesus Himself. Where once we were consumed by earthly pursuits, now as those who have "died" to living for self and sin, and have been raised up by the quickening of the Holy Spirit, we now have new life with new passions and pursuits, all flowing out of a devotion to Jesus Christ.
The apostle Paul seemed to be a fairly busy man, missionary trips, planting churches, writing scriptures, among other things. The truth is all of this flowed out of one thing, the pursuit of the upward call of God in Jesus Christ.
Brothers, I do not consider that I have made it my own. But one thing I do: forgetting what lies behind and straining forward to what lies ahead, I press on toward the goal for the prize of the upward call of God in Christ Jesus.
Philippians 3:13-14 ESV
This is how "seeking first the kingdom of God" should look. Paul was not "beating the air" with a lot of activities, but was disciplined, focused, driven on by a love for Jesus, and a desire to someday stand before Him (1 Cor 9:26). In his pursuit, missionary trips were taken, churches were planted, scriptures were written, along with hardship and suffering, but even this he counted as joy in serving Christ. Paul's focus was on Christ. He didn't dwell in past victories or failures, but always pushed forward. How many of us are defeated by failure? And even more subtle than that, the temptation to relish in the mountain top experiences can sidetrack our pursuit of God as well. We can easily fall into a comfortable complacency if we are not constantly looking forward to the prize. We must move on, the race isn't over yet.
So how are your eyes? How is your focus? The image of Jesus should be sharp and clear, everything else should be fading into the background. If this is not the case for you, it's time to repent, and fix your eyes upon Jesus once again. There is a race to finish, and we need to stay focused.