Teaching kids about giving when money is tight

Been trying to teach my three kids about tithing and generosity but it feels hypocritical when we're living paycheck to paycheck. We still give what we can but I wonder if they're getting the real message or if they're just seeing dad stress about money constantly. Anyone else wrestling with this? How do you model generosity when resources are limited? My oldest asked me why we give money to church if we don't have enough. That one stung a little.