A Barna* survey found that positive attitudes toward missions were linked to personally knowing a missionary. That was the response of the majority surveyed between the ages of 18 and 34. It's always been God's plan for us to be his witnesses "to the end of the earth," Acts 1:8. But lately attitudes have changed, and churches might need to be more intentional in encouraging financial support for their missionaries.
Since there's a positive link between knowing a missionary and supporting missions in general, it's a clear starting point for churches. Get to know your missionaries by regularly communicating with them. Study a little bit about the country where they serve. Pray for them. Getting to know them encourages everyone involved. The missionaries appreciate the interest, and the congregants get more inspired to help them. It may even spark a desire to participate in missions. To learn more about getting involved with the missionaries represented by Global Faith: https://www.globalfaith.net/about/get-involved
More about the research*https://www.barna.com/research/young-christians-value-missions/