In today's gospel reading, Jesus said: "You cannot serve God and mammon." The way of life that Jesus taught His disciples: don't be attached to worldy things, strive to love God and our neighbours, is completely incompatible with a preoccupation with money and possessions. Jesus told us clearly that we can only choose one over the other. If we truly accept Jesus as our Lord, we cannot not be materialistic.
Many people today face lots of stress, some of them go to therapies for this reason. Jesus knows men have lots of anxieties, and so He gave us some excellent advices in the gospel: "Can any of you by worrying add a single moment to your life-span?" He asked us to look at the nature, to encourage us to have faith in God that He already knows all that we need. He wants us to focus on doing God's will, as oppose to wasting our time to worry about those things that we have no control over.
When the devil tempts us to be anxious about our material needs, to not follow God's will, let us remember Jesus' words. Mother Teresa once said: "Yesterday is gone. Tomorrow has not yet come. We have only today. Let us begin." Make the most out of today, follow God's will for you today.