Anxious people miss out on the joy of generosity.

 "Beware of practicing your righteousness before other people in order to be seen by them, for then you will have no reward from your Father who is in heaven. "Thus, when you give to the needy, sound no trumpet before you, as the hypocrites do in the synagogues and in the streets, that they may be praised by others. Truly, I say to you, they have received their reward. But when you give to the needy, do not let your left hand know what your right hand is doing, so that your giving may be in secret. And your Father who sees in secret will reward you.”

Matthew 6:1-4 (ESV)

Those trying to impress others are constantly anxious because their peace comes from what others think of them. But unfortunately, this variable is continuously changing, and is usually fueled by gossip, slander, and politics.
Peace of heart comes when we serve God from a heart of worship, whereas anxiety is a barometer notifying us of an imminent heart storm. As we commit our way to God, we depend upon Him to sustain us, which erases all anxiety. When we give, we bless and imitate our Heavenly Father, who constantly gives.
Anxious people miss out on the joy of generosity and the thrill of being an instrument of God.