I was remarking to someone how hard it can be to really appreciate the gratitude of others. Particularly when we have some idea of how we would like ourselves to be and we find ourselves falling short, or just not "It" whatever "It" is.
But really I think that just gracefully, and gratefully accepting that which is given freely is a benefit to those giving it as well. It can be hard to do. When we have all thees ideas in our head of how were not worthy!
But chances are that if your thinking like that, you are just holding on to some idea that is not going to help you benefit your benefactors one bit.
So do the right thing by them. Placing your hands together and bowing deeply at the waist might be appropriate. Along wit a sincere smile.
I don't know (and don't particularly care) all of the science around it. I'm not particularly concerned about why it works.
But it seems to work pretty well.