What does Matthew 6:34 mean?

Those struggling with addiction, while in recovery, often cling to a set of guiding statements as they work to stay sober. A common mantra used in those situations is "one day at a time." There's no value in that person worrying about whether they will fall to temptation tomorrow. Their addiction must be fought today. Tomorrow's fight will happen tomorrow. In overcoming addiction effectively, such people are taught to focus on winning today's battles.

This is compatible with the principles found in this command from Jesus. He tells His followers not to worry about tomorrow. As He has already said, worry doesn't fix anything. Anxiety over things we cannot control, or out of our reach, makes no sense (Matthew 6:27). God loves us and already knows not only what He wants to accomplish, but what we need to make that happen (Matthew 6:33).

Jesus says, in short, that born-again believers ought to let tomorrow worry about itself. He's not saying Christians cannot or should not make wise plans. Nor is He saying believers ought to literally ignore anything but the most immediate questions. His context here is about the emotions of fear and anxiety. Those who trust in God shouldn't allow wallow in useless worry over the future. Tomorrow's fight will happen tomorrow. The battle to trust God is always happening in the current moment. Today has plenty of trouble with which we need to trust God. Jesus commands His followers to focus on trust for God in a moment-by-moment way. We shouldn't try to solve all our problems, for all time, all at once. Let God provide what is needed day by day.