As mentioned by someone above it is already indoctrinated early on in the Thai, adding that one believes in multiple lives and if one does good in the present, then can come back as a better being in the future.
Had a discussion with my partner about this once that she brings food to the monk several times in the week early in the morning, then she feels better and does it for the future as well.
To my comment that she therefore does it to get better in an afterlife, was denied.
But yes, it does show how you can influence people.