Therefore don't be anxious for tomorrow, for tomorrow will be anxious for itself. Each day's own evil is sufficient. (Matthew 6:34)
We get anxious about so many things of tomorrow and some of it is justifiable, like if we have to go for an important exam or an important blood test that we have been advised by the doctor. But Jesus is not talking about these, but the constant worries of eating, drinking and clothing. These worries only bring more anxiety.
We must judiciously plan for the future regarding many things, but not unduly worry; more so, after trusting in the Lord.
God will provide. We must trust in Him. He is Jehovah Jireh, Our Provider.