This quote is from Matthew 6 verse 34. It’s part of a longer passage about worry that begins at verse 25. In the longer passage, it talks about worrying about acquiring material possessions such as food and shelter. It compares our worry about these things to birds, who also need these things to survive but are much more carefree. However, they manage to acquire these necessities each day. Their creator, God, knows what they need and makes sure those things are provided to them.
Yes, we’re not birds, we’re humans. And unlike the birds, we have bills to pay and various financial constraints and obligations, especially in today’s world. But this passage is not demanding us to have no concept of responsibility, planning, or preparation. However, our worries about tomorrow should not consume our minds to the point that we don’t make room to live today. Especially when the same creator that cares for the birds is also looking after us. Each day has enough worries of its own.