The Gemara and Zohar elaborate in many places that strengthening one's conduct of tznius is an infallible way to be blessed with good health, sustenance, and much nachas - true nachas - from children and grandchildren.

This depends on each and every one of you: that you yourselves act in this manner, and see that your good friends, relatives and acquaintances become aware of the great potential that they possess [to act in a like manner], and the blessings that such behavior brings with it.

Excerpt from Igros Kodesh, Vol. VIII, p. 204