3 John 1:7-8

For these (traveling missionaries) went out for the sake of the Name (of Christ), accepting nothing (in the way of assistance) from the Gentiles. So we ought to support such people so that we may be fellow workers for the truth (that is, for the gospel message of salvation).

Not all of us are called to be missionaries, but we are called to support the workers in the field. Even though we cannot be with them, our support will aid them in their work to spread the message of salvation. We are sowing seed for Jesus through salvations, and without people to spread the Word, the seed would never grow.