One of the ideas that Mark presents is "meddling grandparents." He challenges & encourages grandparents to get involved in their children & grandchildren's faith walk, whether through writing letters/texts/email, making phone calls, & prayer. I love this...probably mostly because I have my own story of how my life has been effected by "meddling."
My great grandma Belsher was an incredible woman of faith. Although we did meet before she passed away, I can't say that I remember as I was still very young. Her legacy, however, lives on, not only in my life but in the lives of nearly all of my Belsher relatives. Great grandma prayed for each one of us every single day. I realize that many grandparents do this, but something to keep in mind is that she had 16 children who lives to adulthood! Praying for everyone in her family was no small feat. Once every three years the Belsher family gathers for a family reunion & it is tradition that on the Sunday of our reunion we have a church service. This was of course birthed & continues all because of great grandma.
I think the greatest way my great grandma has included my faith walk however, is a bit more specific to me. I was a bit of a "miracle baby" as I wasn't my parents first pregnancy. When my great grandma came to visit me as an infant she took me in her arms and said, "All children are a blessing from God, but this is a blessed child." Although I don't remember these words of life being spoken over me, my parents do. I'm fairly confident that now 20-something years later that those words have in fact made a huge impact in my life.
So, to all parents/grandparents/great grandparents out there, who are thinking it's too little too late to have any sort of impact on your children/grandchildren/great grandchildren's faith walk, I would like to encourage you to meddle. Send little notes of encouragement. Make regular phone calls. But most of all pray. You never know what seeds you've planted!