Paul's desire for the believers in Corinth was that they engage in their religious duties and serve God without being distracted, drawn away, or interrupted by the cares of the world.
Thomas Watson in his book "Ten Commandments" writes:
Distraction hinders devotion. The mind is tossed with vain thoughts, and diverted from the business in hand. It is hard to make a distracted heart fix. How often in hearing the Word, the thoughts dance up and down; and, when the eye is upon the minister, the mind is upon other things. Distracted hearing is far from sanctifying the Sabbath. It is very sinful to give way to vain thoughts at this time; because, when we are hearing the Word, we are in God's special presence. To do any treasonable action in the king's presence—is great impudence. "Yes, in my house have I found their wickedness." Jer 23:11. So the Lord may say, "In my house, while they are hearing my Word, I have found wickedness; they have wanton eyes, and their soul is set on vanity!"
To approach God in worship with a distracted mind should be a cause for great concern to the believer. A distracted mind is offensive to God and reveals a heart problem that needs to be fixed. Paul's desire for the believers in Corinth as found in 1 Corinthians 7:35 needs to be our great desire for today -- that we may attend upon the Lord without distraction!
I am currently reading a wonderful little book by Nathanael Vincent (1638-1697) titled "Attending Upon God Without Distraction." This is a gem of a book and provides insight into both the cause and the treatment for the disease of distraction. If looking for a book on this subject there is no better treatise on the subject than what Nathanael Vincent offers.