Aure audietis, et non intelligetis: et videntes videbitis, et non perspicietis. These are the clear words of the Holy Spirit: they hear with their own ears, and they do not understand; they see with their own eyes, but they do not perceive.
Why worry if some, although they see the apostolate and they know how great it is, still do not give themselves to it? Pray in peace, and persevere along your way. If they don’t want to set out, there will be others!